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Design of vacuum components for FERP-technique characterization systemINTERNSHIP REPORT MECHANICAL ENGINEERING DESIGN ENGINEERING

Gerben Groeneveld s1013823

08-08-2016

Internship report ME

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Design of vacuum components for FERP-technique characterization system

Internship report Master Mechanical Engineering

Gerben Groeneveld

s1013823

CTI Renato Archer

Rodovia Dom Pedro I (SP-65), Km 143,6 – Amarais,

Campinas – SP, CEP 13069-901, Brazil

Surface Interaction & Display Division, DMI

Campinas, state of São Paulo, Brazil

06-01-2016 to 06-04-2016

Vinicius L. Pimentel

dr. ir. Wessel W. Wits

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08-08-2016

University of Twente

Faculty of Engineering Technology

Design, Production and Management – Design Engineering

De Horst (building 20), room N204

Postbus 217

7500 AE Enschede

The Netherlands

Student:

Student number:

Company name & address:

Division:

Internship location:

Internship period:

Mentor CTI:

Supervisor University of Twente:

Report pages (excl. appendices):

Appendices:

Date:

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Preface

This document describes the findings of an internship carried out be me at the Center of

Information Technology (CTI) in Campinas-SP, Brazil. This internship lasted from the January to the

start of April 2016 and is part of the Master Mechanical Engineering from the University of

Twente, Enschede, the Netherlands.

I traded the cold winter in the Netherlands for a burning Brazilian summer and ended up in a

culture of samba, churrascu and caipirinhas. On these hot summer days, the air-conditioning in the

laboratory of DMI was a welcome treat. Here it was, that I spent my time on a vacuum study and

contributed to the future FERP-research system, as described in this report. I want to thank

Vinicius, Mamoru and all the other colleagues at DMI for their helpful knowledge, constructive

support throughout the project, but also the fun we had together. I had a wonderful time in Brazil

with a lot of new experiences, cultural and technical. The Brazilians made me feel very welcome,

which makes that I am wistfully watching the Olympic Games of Rio 2016.

This document is the result of the technical experiences that I had in Campinas. To the reader: I

hope this report may be interesting to read and contain well-explained information.

Groningen, the Netherlands

August 2016

Gerben Groeneveld

Me and internship supervisor Vinicius L. Pimentel with brand-new

vacuum equipment in the laboratory of DMI.


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Abstract

In the laboratory of DMI, the display division of CTI, research is carried out to find out the work

function of materials using the FERP-method. For this method is an ultra-high vacuum (UHV)

environment needed. The laboratory of DMI currently has a FERP-setup that is specified for high

vacuum (HV). This setup functioned as a ‘proof of principle’, in order to show that the laboratory is

able to carry out this kind of research. With the successful outcome of earlier FERP-experiments,

the research can now be improved. A concept is created for an UHV-system that enables more

accurate results. With the new system, DMI wants to achieve the pressure level of 5x10-12 Torr

(for readability pressure levels are presented in this format).

A CAD-model of the new UHV-concept is used by DMI to acquire budget for the required

commercial components. In early 2016, all commercial components are arrived and need to be

connected by specified nipples. The existing CAD-model featured these connections, but not yet

dimensioned and detailed for manufacturing. These detailed designs are provided within this

internship. First, a study into vacuum principles and equipment is carried to be able to describe

the complete FERP-system accurately. Here it is described that vacuum is the state of a gas with a

pressure level below the atmospheric pressure. In vacuum technology, there are different regimes

distinguished, based on a difference in molecular behavior. HV and UHV are the two regimes with

the lowest pressures, below 1x10-6 Torr. The difference between vacuum regimes implies the use

of different pumping- and measurement principles. This means that a range of pumps and gauges

needs to be used to reach the desired UHV-level. Besides this, different commercial components

as gate valves, a TSP-Cryoshroud, spheres and a transfer arm are used in the setup.

After the study of vacuum principles and equipment, the required designs for the connections are

formulated. These designs are subject to industry standards and limited dimensions. The designs

for 5 nipples and 1 crossing are provided. The commercial components and newly designed

connections are combined in a new CAD-model of the complete setup. The final setup must be

placed onto an existing support structure in the laboratory of DMI. With CAD-software it is

checked that this is possible. With the technical drawings for the connections and the complete

CAD-model, the new FERP-system can be built. This is done by DMI in the future, as soon as

required budget for manufacturing is available.

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Table of contents

1 Introduction ........................................................................................................... 6

1.1 Assignment .......................................................................................................................... 6

1.2 Company and division – CTI and DMI ................................................................................. 7

1.3 Report build-up ................................................................................................................... 9

2 Theory .................................................................................................................. 10

2.1 FERP ................................................................................................................................... 10

2.2 Theory of vacuum.............................................................................................................. 11

2.2.1 Definition of vacuum ................................................................................................. 11

2.2.2 Vacuum regimes ........................................................................................................ 12

3 Equipment ............................................................................................................ 15

3.1 Vacuum pumps .................................................................................................................. 15

3.1.1 Diaphragm pump ....................................................................................................... 16

3.1.2 Turbo-molecular pump ............................................................................................. 16

3.1.3 Ion pump ................................................................................................................... 17

3.1.4 Other types of pumps................................................................................................ 18

3.1.5 Pump sequence ......................................................................................................... 19

3.2 Vacuum gauges ................................................................................................................. 20

3.2.1 Pirani - thermocouple gauge ..................................................................................... 20

3.2.2 Penning gauge ........................................................................................................... 21

3.2.3 Ion gauge ................................................................................................................... 21

3.3 Vacuum flanges ................................................................................................................. 22

3.3.1 KF Flanges .................................................................................................................. 23

3.3.2 CF Flanges .................................................................................................................. 23

3.3.3 Sizes and versions of CF-flange ................................................................................. 24

3.4 Other equipment ............................................................................................................... 25

3.4.1 Spheres ...................................................................................................................... 25

3.4.2 Viewport .................................................................................................................... 26


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3.4.3 Gate valves ................................................................................................................ 26

3.4.4 Transfer arm .............................................................................................................. 26

3.4.5 Residual Gas Analyzer ............................................................................................... 27

3.4.6 TSP Cyroshroud ......................................................................................................... 27

3.5 Outgassing and bake-out .................................................................................................. 28

4 Design .................................................................................................................. 29

4.1 From quick concept to final design ................................................................................... 29

4.2 Requirements .................................................................................................................... 30

4.3 Crossing ............................................................................................................................. 31

4.3.1 New crossing design .................................................................................................. 32

4.3.2 Crossing part dimensions and production ................................................................ 34

4.4 Nipples ............................................................................................................................... 37

4.4.1 Nipple between main chamber and crossing ............................................................ 38

4.4.2 Nipples between small sphere and main chamber ................................................... 39

4.4.3 Nipples between small sphere and turbo-molecular pump ..................................... 46

4.5 Top flange for main chamber ............................................................................................ 48

5 Assembly .............................................................................................................. 49

5.1 CAD-model of complete setup .......................................................................................... 49

5.2 Procedure before FERP-experiment ................................................................................. 50

5.3 System weight and support structure ............................................................................... 51

5.3.1 List of system components and weight ..................................................................... 51

5.3.2 Support structure ...................................................................................................... 51

6 Conclusion & recommendations ........................................................................... 55

7 Reflection on the internship.................................................................................. 56

References .................................................................................................................. 58

Appendix A – Pump pressures ..................................................................................... 61

Appendix B – RGA spectrum ........................................................................................ 62

Appendix C – Standardized tube sizes .......................................................................... 63

Appendix D – Technical drawings ................................................................................. 64

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1 Introduction

With a new research setup in the laboratory of DMI, the FERP-method will be applied to retrieve

work functions of materials. A vacuum environment is needed for this method. The research setup

is not yet completed. This report describes the findings of an internship, in which a study is done

to the required vacuum components of the new setup. Designs are made for required connections

between commercial components and in the end a complete CAD-model of the new setup is

provided. This sections introduces the assignment motive, company and division in more detail.

1.1 Assignment This internship assignment starts, where another assignment ended. The previous assignment was

carried out at CTI in 2014 by University of Twente student Jildert Anema. He contributed to the

development of an initial setup for work function research by the FERP technique. He designed

and combined the models of the required vacuum components. The end product was a complete

CAD-model of this system, that was specified for high vacuum pressures (HV).

After this, a new ‘dream’ system was designed. A CAD-model of this setup was used to obtain

budget for this project from CTI management. With approval for the project, the received budget

was used to purchase required commercial components. In theory, this new system enables FERP-

research at operating pressures of about 5x10-12 Torr, in the ultra-high vacuum regime (UHV).

Figure 1.1 shows the high vacuum FERP-system and the new UHV-concept.

Figure 1.1 – HV-system in DMI laboratory (left) and CAD-model of new UHV-concept (right) (1)

There a two main reasons to upgrade from a HV-setup to UHV. Firstly, in the lower pressures of

UHV, there is less probability of contamination interfering with the research results. The obtained


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work functions will be more accurate. Secondly, DMI wants to extend the possibilities of the

laboratory. The new UHV-setup could for instance be used for electron microscopy applications.

Here starts this internship assignment:

The existing CAD-model of the UHV-concept only functioned to receive budget for commercial

components. This model was a quickly built, why no detail was spent to the design of the

connections, called nipples in vacuum technology. To be able to build the new concept, these parts

need to be detailed within the physical constraints of the system. This report describes the design

and development of these parts. In the end, the commercial components and designed parts are

combined in a new detailed CAD-model of the complete research setup. Again, the final model is

used to request budget for manufacturing.

The desired level of detail consists of technical drawings to be used for manufacturing. The nipples

need to be designed specifically for this setup. They cannot be purchased as the other commercial

parts. Manufacturing is done at either the CTI workshop or an external manufacturer.

The goal of this assignment as formulated by internship supervisor Vinicius L. Pimentel was to

detail the components to be machined in the CTI workshop and track their manufacturing. Due to

budget constraints however, manufacturing is not carried out during the internship period. The

designs made is this report now have the function to obtain required budget as soon as possible,

in order for the FERP-system to be completed.

The goals of this internship can be summarized as follows:

1. Design of new parts and inclusion of commercial components in research setup up to:

- Precise presentation (CAD) of complete new setup to acquire budget

- Detailed technical drawings of designs to be used for manufacturing

2. Carry out a study about vacuum technology, principles and equipment

1.2 Company and division – CTI and DMI This internship is carried out at the company CTI, or Centro de Tecnologia da Informação Renato

Archer. Translated: Center of Information Technology “Renato Archer”. CTI is located in Campinas

in the state of São Paulo, Brazil. It is a research unit of the Ministry of Science, Technology and

Innovation (MCTI), and therefore a government funded institution. Research focuses on IT, micro-

electronics, displays, software and automation. The goal is to develop new innovations and

technologies. This way, CTI provides a link between the academia and technological industry in

Brazil (2).

CTI has a large facility with currently 11 buildings in which different divisions are housed. The

assignment described in this report was provided by DMI, or Divisão de Mostradores de

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Informação, the Surface Interaction and Display Division. DMI’s research concerns for instance the

development new types of displays, solar cells and organic electronics. The FERP-system of this

project focuses on obtaining the work function of materials, which is a useful property in display

manufacturing. This report often refers to ‘DMI’, as it is the most important actor. Figure 1.2

shows the laboratory of DMI where the FERP-research takes place, the workplace of internship

supervisor Vinicius L. Pimentel. Other DMI laboratories are mostly designed for chemical research

purposes.

Figure 1.2 – DMI laboratory where FERP-system is located

Budget cuts at CTI

In the current economic crisis in Brazil in early 2016, budget cuts are frequent and there are only

few possibilities for expenses by CTI. To illustrate this: in the last quarter of 2015, the CTI board

was forced to economize by closing the company restaurant and removing the option for a free

private bus towards the premises for employees without cars. This affects for instance the travel

of student employees from university UNICAMP and foreign interns like the ones from the

University of Twente.

The small budget available also affects this project. All designs described in this report need to be

manufactured by either the CTI workshop or an external manufacturer. The first option is the most

cost-effective one, but the workshop has to purchase raw material to produce the parts. The

budget needed is simply not available. Due to this, the designs suggested in this report only exist

up to CAD-level and need to be produced whenever budget is available. When this is the case is

not known. However, because the expensive commercial parts for the FERP-system are already

purchased, it is to be expected that the smaller budget required for these last parts to complete

the setup, is easily appointed by CTI management.


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The economic and political crisis in Brazil affects everyone in the country, but a government

funded company as CTI may suffer even more. It was unfortunate to get to know that some

colleagues at the DMI division had to leave the company in the last part of 2015.

1.3 Report build-up This first chapter provided the introduction. The next chapter focuses on the theory: the FERP-

research is shortly discussed and the principles of vacuum are explained. Chapter 3 focuses on the

commercial vacuum components and their working principles, part of the study into vacuum. In

chapter 4 the designs to complete the setup are proposed. Chapter 5 describes the combination of

the commercial components and new designs into a complete CAD-model of the new FERP-

system. Also in this chapter, a support structure for the new system is discussed. The last chapters

6 and 7 include the conclusion and the reflection on the internship.

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2 Theory

2.1 FERP The purpose of the future vacuum research setup in the laboratory of DMI, is to function for FERP-

research and electron microscopy. Although it is not the objective of this project to understand

the physical underlying principles of these methods, it is useful to get some insight in the type of

research carried out. For the completeness of the report, the FERP method is shortly discussed.

FERP is short for Field Emission Retarding Potential. It is a method used to obtain the work

function of material. A FERP-setup consists of a triode, featuring a cathode (emitter), gate and

anode (collector) (3). Figure 2.1 shows a model in which the cathode is indicated as CNT.

Figure 2.1 – elements of FERP-setup (3)

FERP can be split in Field Emission (FE) and Retarding Potential (RP). The first part is Field Emission.

To this end, a single atom tip cathode is used. By applying a high voltage (500V) on the grid (first

disk), electrons are released from the tip. The second disk is grounded, which ´brakes´ the

electrons. This second disk features a smaller aluminum disk with a gap to let only electrons pass

with a path perpendicular to the surface of the sample. The use of a magnet in the first disk helps

to focus the electron paths on the collector. A cloud of electrons is formed. They cannot reach the

anode unless a forward potential is applied. This is the second part: Retarding Potential.

To this end, the voltage over the sample or collector is increased. The floating electrons only jump

towards the sample if the voltage is high enough to attract them. Once this happens, a peak is

observed in the grid current, measured by an Ampere meter. This peak represents the work

function of the sample material.

For different kinds of sample material, a different forward potential needs to be applied. The work

functions of materials can this way be obtained a collector current vs. applied voltage plot, as seen

in Figure 2.2. The work functions for nickel (A & B) and gold (C) are indicated here by the small

arrows on the bottom axis.


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Figure 2.2 – obtained work functions for different sample materials (4)

A high to ultra-high vacuum is required for the FERP research. The path of the electrons must be

free of any other molecules, which interfere. In the UHV-concept, the FERP-head is placed on top

of the main chamber (the large sphere in Figure 1.1). This head contains the electron tip, the grid,

the collector etc. as seen in Figure 2.1. A plate with the sample material for which the work

function is determined must be placed in the collector location. This sample is introduced using a

transfer arm. This procedure is discussed later on in this report.

For a detailed description of the FERP-method and its underlying principles of quantum physics,

the reader is advised to consult dedicated literature (3, 5).

2.2 Theory of vacuum It is mentioned that a vacuum is needed for the FERP-research. The theory of vacuum forms the

basis for how the new research setup is built and needs to function. It is essential to understand

the principles of vacuum, to be able to understand what happens in the system to be designed.

2.2.1 Definition of vacuum Thorough understanding of vacuum starts with knowing the scientific description. Different

sources of literature provide a slightly different approach, but are in essence the same. A gas is

said to be in vacuum when its pressure level is below a certain value: the minimum air pressure on

earth. Some take the air pressure at sea level or atmospheric pressure (1 atm = 750 Torr) for this

value (6), while others state more precisely that a gas is only in vacuum when its pressure is below

225 Torr (7), the lowest possible air pressure on the surface of the Earth, on top of the Mount

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Everest. In the foregoing project carried out by Jildert Anema (1), the first approach is taken. The

following definition of vacuum is also given here:

Vacuum describes the state of a gas in a chamber, of which its pressure is lower than

the pressure in the surrounding space. In this project a gas is said to be in vacuum

when its pressure is below 750 Torr.

Just below the 750 Torr boundary of vacuum, a gas is said to be in rough vacuum. Process

pressures used in industrial applications of vacuum are mostly in the order of 7.5x10-3 Torr to

7.5x10-5 Torr (8), which is in medium to high vacuum. The ultra-high vacuum pressure desired for

the new setup at DMI is very much lower: 5x10-12 Torr. A distinction between these vacuum

regimes is made, because of the difference in molecular behavior seen at the reduction of

pressure.

Note that gas pressure can be given in many different units. The atmospheric pressure at sea level

is for instance 1 atm ≈ 100,000 Pa ≈ 1000 mbar ≈ 750 Torr. The standard unit used in

documentation of DMI is Torr, according to the American unit system. This unit is therefore used

in the continuation of this report.

2.2.2 Vacuum regimes

The difference in vacuum regimes is based on the amount of gas particles still present in a system.

The molecular behavior in a rough vacuum, just below the 750 Torr level, is completely different

from the behavior of the leftover gas particles in the higher vacuum levels. This makes obtaining

and maintaining a vacuum a challenging process.

To categorize the molecular behavior, a total of 4 different vacuum regimes are distinguished. The

corresponding pressure ranges are given in Table 2.1. The boundary of each region cannot be

rigidly defined, but these terms are useful when discussing the actions of molecules inside the

vacuum system (6).

Vacuum stage Pressure range

Rough Vacuum 760 Torr to 75 milliTorr

Medium (Process) Vacuum 75 milliTorr to 1x10-6 Torr

High Vacuum 1x10-6 Torr to 1x10-9 Torr

Ultra-high Vacuum below 1x10-9 Torr

Table 2.1 – pressure ranges of vacuum regimes (8)

The table shows that the desired vacuum level of 5x10-12 Torr lies far within the ultra-high

vacuum regime. To obtain this pressure level, the new system needs to pass all the pressure

ranges from atmospheric pressure. It is required to understand the principles of the different

vacuum regimes to design a robust system that can handle them all.


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Rough Vacuum

The first stage of vacuum is a rough vacuum, with pressures just below the atmospheric pressure.

There are still lots of gas particles present in a vacuum chamber, interacting with each other

following the laws of thermodynamics (8). This regime is characterized by viscous flow, which is

graphically represented in Figure 2.3a. The fluid flow pumps used to obtain these vacuum levels,

function to remove the bulk material from the vacuum chamber. These are the type of pumps well

known to mechanical engineers, that is why they are often referred to as mechanical pumps.

Figure 2.3 – viscous and molecular flow (8)

Medium Vacuum

The second regime is called medium vacuum, present in many industrial applications of vacuum

(8). Pressures are in the range of 75 milliTorr to 1x10-6 Torr. The flow regime in this vacuum stage

is called transition flow. This is a very complex regime between the viscous and the molecular flow,

which is seen in even lower pressures. With the use of specified vacuum pumps, the transition

from viscous flow to molecular flow is often short. The molecular behavior in this transition cannot

be described accurately, because there is a random factor present.

In case of a medium vacuum in industrial processes, often a high vacuum is created first. After that

a gas is injected which increases the pressure again towards a medium vacuum. This gas is added

for the purpose of the process or experiment.

High Vacuum (HV)

When reducing the pressure from a medium vacuum further, the high vacuum regime is reached.

This vacuum regime is used in the FERP-experiments currently carried out in the laboratory of

DMI, because the setup is limited to these pressures. The HV-regime is dominated by the

molecular flow, shown in Figure 2.3b.

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The molecular flow features far more molecule-chamber wall collisions than molecule-molecule

collisions, because the chamber dimensions are far greater than the mean free path of the leftover

molecules (8). This means that another pumping principle needs to be applied. High vacuum

pumps are statistical pumps; they do not suck the molecules out of the chamber, but rather wait

until a molecule reaches the pump to be removed from the chamber. High vacuum pumps are not

appropriate for higher pressure gasses and cannot be exposed to atmosphere. These type of

pumps must therefore be backed by mechanical pumps. A combination of mechanical and high

vacuum pumps must be applied to obtain and maintain a high vacuum.

Ultra-high vacuum (UHV)

Ultra-high vacuum is the ultimate regime described in vacuum science, covering the lowest

pressures. This is the desired regime for the future research setup at DMI. High vacuum and ultra-

high vacuum are both dominated by the molecular flow, but in UHV more residual gasses have

been removed from the chamber. To reach the pressures below 1x10-9 Torr, focus lies on

removing the gas load from the chamber walls. This gas load can be recognized in Figure 2.3b.

Furthermore, the dominant molecule in high vacuum is usually water, while UHV is almost 100%

dry and contains hydrogen as the most prevalent residual gas. Hydrogen is light and mobile and

very difficult to pump (8). To remove water and gas load from the walls, additional equipment is

used. For instance, a TSP or Titanium Sublimation Pump, explained in section 3.4.6. Also

procedures like a bake-out are required, see section 3.5.

It can be concluded that there is a vast diversity of molecular behavior in the different vacuum

regimes. This imposes the use of different pumping principles to reach the low pressures of an

ultra-high vacuum. The correct sequence of pumps is essential here. Multiple pumping techniques

are explained in the next chapter. These need to be included in the final research setup.


15

3 Equipment

The future setup at DMI will be built from equipment that is already present in the laboratory.

Parts from the current setup and newly purchased parts are combined into a larger configuration

that is appropriate for UHV research. This chapter elaborates on the required equipment and

explains working principles and properties. Vacuum pumps, gauges, flanges and other equipment

are reviewed. Understanding the functions and limits of the required equipment is formulated as

one of the internship goals by CTI and therefore an extensive part of this report.

3.1 Vacuum pumps Due to the different molecular behavior in the four vacuum regimes described before, different

types of pumps need to be applied to be able to achieve the UHV level. Figure 3.1 shows the

typical operating pressures for different types of pumps. Remember that an ultimate pressure of

5x10-12 Torr is desired for this project. The figure reveals that surely an ion pump is needed to

achieve this goal.

Figure 3.1 – Typical pump pressures (6)

The correct sequence of pumps turns out to be very important. In the new setup a dry mechanical

diaphragm pump, a turbo-molecular pump and an ion pump are applied. These pumping principles

are explained.

Some useful properties to identify vacuum pumps are the compression ratio, ultimate pressure

and pumping speed. The compression ratio is the ratio of the outlet pressure over the inlet

pressure. The pumping speed or volume flow rate is mean volume flow measured at the inlet of a

vacuum pump. This is given in liters per second (L/s). Pumps for lower pressure ranges have higher

volume flow rates, but transfer less gas molecules per second, due to the lower pressure. The

ultimate pressure is the highest pressure at which a vacuum pump can theoretically operate. The

values for these three properties are strongly dependent on the pumping principle.

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3.1.1 Diaphragm pump

A diaphragm pump is a dry mechanical pump used in the lower vacuum regimes with higher

pressures, as can be recognized in Figure 3.1. This type of pump makes use of a flexible membrane

that is driven by a crank. The membrane is an air-tight seal between the suction chamber and the

mechanical driving system, which ensures a dry way of pumping gasses out. There is no oil

contamination. Figure 3.2 shows the working principle of a 2-stage diaphragm pump. When the

crank moves down, gasses from the vacuum chamber get sucked in at the inlet. When the crank is

in outmost downward position, the inlet valve closes. Then the crank moves up, opening the

outlet valve and pushing the gasses out of the suction chamber. This way, the pump creates a

pressure gradient in the vacuum chamber, which causes gas molecules to diffuse towards the

inlet. The diaphragm pump can be used the other way around as compressor. A clear animation of

the working principle of a diaphragm pump can be found at the website of Thomas by Gardner

Denver (9).

Figure 3.2 – 2-stage diaphragm pump working principle (10)

Due to its design, the diaphragm pump has a limited compression ratio. An ultimate pressure of

around 50 Torr can be achieved by a one-stage pump. Connecting multiples stages can decrease

the ultimate pressure up to 0.4 Torr (11). Figure 3.2 shows for instance two stages in series. The

diaphragm pump that is used in the laboratory of DMI is a MVP 015-design by Pfeiffer Vacuum

with a pumping speed of 15 L/min, see Appendix A. This pumping speed is merely limited by the

dimensions of the suction chamber.

3.1.2 Turbo-molecular pump The second pump type used in the future setup is a turbo-molecular pump. The design of this

pump is similar to that of a turbine: multiple rotating bladed disks are lined up in a housing. The


17

blades rotate at very high speeds. Gas molecules from the vacuum chamber are then absorbed by

the blades and after period of time transferred in the direction away from the chamber. The

blades must not be slowed down from impact by other molecules, therefore the mean free path

must be greater than the blade spacing. This is the case in the molecular flow regime (12).

The turbo-molecular pump is a so-called kinetic pump. This type of pump suffers from a backflow

caused by counter-pressure. The volume flow rate decreases with increasing pressure and

becomes 0 at maximum compression ratio. The principle of a turbo-molecular pump is better

suited for high mass molecules. The compression ratio and pumping speed for hydrogen (H) are

significantly lower than for nitrogen (N). The principle is not appropriate for the viscous flow

regime, which arises at the outlet of the pump for high compression ratios. Hence, a backing pump

is needed here. At DMI the turbo-molecular pump and diaphragm pump are therefore always

connected in series.

The turbo-molecular pump used by DMI is the HiPace® 80 by Pfeiffer Vacuum, see Figure 3.3. The

bearings of the rotor of this pump are designed as such, that the lubricants cannot contaminate

the vacuum chamber. The rotor has a maximum speed of 90,000 rpm. The pump has an ultimate

pressure of 3.75x10-10 Torr. The volume flow rate (for Nitrogen) is 67 L/s. This is much higher than

the pumping speed in L/s seen for the diaphragm pump, but one must realize that the turbo-

molecular pump operates in lower pressures and hence the speed in molecules per second lies in

comparison lower.

Figure 3.3 – HiPace 80 turbo-molecular pump by Pfeiffer vacuum

3.1.3 Ion pump

An ion pump is applicable in lower pressures and must be used to achieve UHV. This is a type of

pump of the gas-binding class (13). This classification can be immediately made clear by explaining

the principle. In comparison to the earlier explained pumps, the ion pump does not pull gas

molecules towards the pump inlet. The pump has to wait for the moment that a gas molecule

floats into, in order to absorb it.

Figure 3.4a shows the interior of an ion pump. It features a honeycomb-like structure of positively

charged circular anode rings. This structure is placed in a magnetic field. On the outside of the

anode structure, titanium plates are placed that function as the cathodes. When the ion pump is

activated, free electrons start to make helical movements inside the anode. This is called

18

magnetron motion (14). The electrons are bound to hit gas molecules that enter the ion pump

from the vacuum chamber. On collision of a free electron with a gas molecule, a positively charged

ion is formed. This ion accelerates towards the titanium cathode. When the ion hits the cathode

with great speed, sputtering occurs. The gas ion is absorbed in the cathode, while titanium

compounds are sputtered on the anode surface. It is seen over time that the anode surface gets

covered by a small titanium compound layer, which forms the cover that prevents release of gas

molecules back into the system. The titanium cathode plates get saturated by absorbing the gas

molecules. This is why they need to be replaced after a period of use. Based on this information, it

is clear why an ion pump cannot be exposed to high pressures. The cathode plates would get

saturated very fast and become unusable. The ion pump principle is nicely explained by Gamma

Vacuum (14).

Figure 3.4 – a) ion pump interior (15) and b) 400L ion pump exterior (16)

DMI owns the TiTan 400L ion pump by Gamma Vacuum, shown in Figure 3.4b. For this type of

pump, no speed or compression ratio can be specified because of its absorption principle. The

starting pressure is specified as 75x10-4 Torr, at the start of the HV regime. The ultimate pressure

lies below 1x10-12 Torr (16), which is required for the goal pressure of this project.

The ion pump was specifically purchased for the new FERP-system. The current research setup in

the laboratory features the diaphragm pump and the turbo-molecular pump and is for that reason

only specified for high vacuum. Once the ion pump is added, the step towards ultra-high vacuum is

made easily. However, the desired vacuum level is 5x10-12 Torr. Professional use and strict design

of the new research setup is therefore demanded. The use of the correct flanges and additional

equipment like the TSP is very important here.

3.1.4 Other types of pumps

Besides the three vacuum pumps used by DMI, there is a wide range of pumps with different

pumping principles available. Examples are the rotary vane pump, roots pump and scroll pump for

low and medium vacuum. Cryogenic and diffusion pumps can be used in the higher vacuum

regimes. And even more vacuum pump technologies exist. Several companies offer extensive

information on these types of pumps (10, 15). Reason for DMI to not apply these is often out of


19

cost consideration. The other important reason to not use a pump is the possibility of lubricants

entering the vacuum chamber. This is for instance seen for the rotary vane pump, a so-called wet

pump with a mechanism based on oil. For UHV application at DMI, the use of dry pumps is

essential. This is case for the diaphragm pump, turbo-molecular pump and ion pump.

3.1.5 Pump sequence

In the foregoing sections it is seen that the different pumping principles are applicable in a certain

pressure range. To conclude the information on vacuum pumps, the sequence of pumps for the

new setup at DMI can now be clarified. To this end, see Figure 3.5. Here the relative pumping

speed for different pumping principles is set out against the pressure in Torr.

Figure 3.5 – relative pumping speed (17)

It is seen that the diaphragm pump (purple line) loses functionality fast with decreasing pressure.

The turbo-molecular pump (red line) becomes effective once the molecular flow regime is

reached. Its ultimate pressure around 1x10-11 Torr is not presented in this graph. The ion pump

(blue line) becomes useful at lower pressures and can reach a theoretical pressure below 1x10-13

Torr. The entrapment principle of this pump also works on higher pressures, but this would result

in saturated cathode plates which would make the ion pump unusable very fast. The blue line does

for that reason does not represent a possible relative pumping speed, but rather an advice on

when the ion pump should be activated.

The sequence of pumps is in practice more difficult than just activating one pump after the other.

Different sections of the future setup are separated by gate valves to ensure that the HV and UHV

pumps are not exposed to dangerous higher pressures. The correct sequence of pumps and valves

is discussed at the point where the complete configuration is presented, see section 5.1.1.

20

3.2 Vacuum gauges Pumps are used to generate a vacuum, but cannot indicate which vacuum level is reached.

Vacuum gauges are used for this purpose. As was seen with the vacuum pumps, also for gauges

holds that different types are only applicable in a certain range of pressure. Multiple gauges are

needed to describe the complete pressure range from atmospheric pressure to the desired UHV

level of 5x10-12 Torr.

Direct gauges measure the pressure independently of the composition of the gas being measured.

Indirect gauges are dependent on the composition of the gas being measured, such as the thermal

conductivity (6). Indirect gauges need for that reason to be calibrated, dependent on the gas

mixture present in a system. In the future setup three gauge types are included: Pirani, Penning

and Ion Gauges.

3.2.1 Pirani - thermocouple gauge

The first gauge of interest is the Pirani – thermocouple gauge. There is a slight difference between

these gauges based on manufacturer, but they work following a similar principle. The Pirani gauge

is an indirect gauge. The measurement is based on the thermal conductivity of the gas it is placed

in. A hot wire in a tube is placed in the gas, another wire placed in a reference gas. The wires are

connected in a standard ‘Wheatstone bridge’ (6), see Figure 3.6. The first wire loses heat to the

gas around it. While the temperature of the wire is maintained, is the current needed to do this

the measure for gas pressure. If the pressure is high, there are a lot of gas molecules to transfer

heat and the wire loses heat fast. If the pressure decreases, there a fewer gas molecules to

transfer heat and there is a lower electrical current required to maintain the temperature of the

wire constant. Hence, the electrical current required is an indirect measure of the vacuum level. At

pressures below 1x10-4 Torr there is so little gas present that the gauge cannot provide an

accurate reading (6). The composition of the gas significantly affects the reading (accuracy) of

these gauges. Normally the gauges are calibrated for air (78 percent nitrogen) and a factor must

be applied to the reading for argon, helium, or hydrogen. Argon absorbs heat much faster than

nitrogen, while nitrogen is much faster than helium or hydrogen. As the pressure decreases the

offset due to the gas composition decreases as well (6).

Figure 3.6 – Pirani gauge and Wheatstone bridge (6)


21

3.2.2 Penning gauge

The Penning gauge is also called a cold-cathode ionization gauge, which relates to its working

principle. The gauge features a confined cold cathode and an anode placed inside a magnetic field.

Ions present in the gas accelerate towards the cathode and upon interaction release electrons.

The low pressure and high voltage cause a plasma discharge with an electron bombardment

towards the anode. Due to the magnets placed outside the cathode, the electrons move along a

helical path, which increases their effectiveness (18). If the gas molecules are hit, they are ionized

and accelerate towards the cathode. Ion impacts on the cathode are measured and reported by

the electronics of the gauge (6). Penning gauges are significantly influenced by the gas

composition and thus of the indirect type. Because a glow discharge is required for this type of

gauge to operate, it does not work at pressures above 1x10-2 Torr. Some inverted magnetron

cold-cathode gauge types are specified for pressures up to 1x10-11 Torr, in the UHV-regime (19).

3.2.3 Ion gauge

The Ion gauge is also called a hot-cathode ionization gauge. The working principle lies close to that

of the Penning gauge. For this gauge type, often the Bayard-Alpert design is used. The Bayard-

Alpert gauge applies a heated filament cathode as the source of electrons. These emit towards an

anode grid. On their way from the emitter towards the anode grid, the electrons ionize gas

molecules. These molecules accelerate towards a nearly grounded ion-collector. The impact of

ions creates a current which is measured by the electronics. At a constant filament-to-grid voltage

and electron emission current, the rate that positive ions are formed is directly proportional to the

pressure in the gauge for pressures below approximately 1x10-3 Torr (20). The hot cathode

principle of the Ion Gauge extends the readable pressure range of the Penning principle.

The Bayard-Alpert gauge used by DMI is the UHV-24p design from Agilent Technologies, see Figure

3.7 on the next page. The limit of this gauge lies at 5x10-12 Torr. This explains the limit set for this

project. The vacuum level of 5x10-12 Torr is the minimum pressure for which an accurate reading

can be given by the used equipment. For the pressure range between atmosphere and 1x10-9

Torr, DMI uses a combination gauge of Pirani and inverted magnetron cold-cathode technique,

installed on the sample introduction chamber, see section 5.1. On the main chamber, a Pirani

gauge and the hot-cathode Bayard-Alpert gauge are installed.

Direct gauge example: capacitance manometer

The three explained gauges where all of the indirect type. To show the existence, an example of a

direct type of gauge is the capacitance manometer. This gauge makes use of a diaphragm and a

reference pressure. Based on the pressure in the vacuum chamber, the diaphragm either extends

or compresses. Deflection of the diaphragm is measured as the change in capacity of a plate

capacitor. With this principle, an accurate pressure reading can be given up to 1x10-4 Torr (21). In

the setup at DMI, a Pirani gauge is already used for this pressure range.

22

Figure 3.7 – Bayard-Alpert design Ion gauge in DMI laboratory

3.3 Vacuum flanges Up to this point a description of a range of vacuum pumps and gauges is given. This equipment,

like all other vacuum equipment, needs to be connected in a vacuum system somehow. A

connection between vacuum parts needs to be airtight to retain the low pressure inside. Different

standards are developed for this purpose.

Two types of standard vacuum flanges are found in the laboratory of DMI. There are the KF- and

CF-flanges. KF-flanges feature a rubber ‘o-ring’ as the seal for airtight connection. In CF-flanges,

this function is provided by a soft metal gasket, made from copper in most cases. Figure 3.8 shows

the two different types and corresponding airtight seals in the inventory of DMI.

Figure 3.8 – KF (left) and blank CF flange (right) and corresponding seals


23

3.3.1 KF Flanges

KF is short for Klein Flange. Figure 3.9 shows an exploded view of this flange type. The two tubes

on the outside are connected to other parts of a vacuum setup, for instance a pump or chamber.

The black ring is a rubber o-ring, which functions as the airtight seal. It is placed around a

centering-ring that aligns the flanges and holds the o-ring in position. The connection is hold

together by the clamp, which closes by tightening the wing nut.

Figure 3.9 – exploded view KF-flange (22)

KF flanges are appropriate for pressures to 1x10-8 Torr (23), so UHV cannot be reached. This type

of flange suffers from outgassing. Gas molecules trapped in the o-ring escape in the lower

pressure ranges. The use of KF-flanges is cost-effective, because the o-ring seal can be re-used.

This is not the case with CF-flanges, as explained below. The low price made this type of flange

interesting for DMI for the old research setup, but is due to its limits not applied in the future

system.

3.3.2 CF Flanges The CF-flange type was developed by Agilent technologies and set a new standard for vacuum

applications. CF is short for ConFlat, a name variation on the older KF type. CF-flanges are tested

for pressures to 1x10-13 Torr (24), therefore ideal for the UHV application as desired by DMI.

Figure 3.10a shows the exploded view of a CF-flange, Figure 3.10b shows the mated cross section.

Figure 3.10 – a) exploded view of CF-flange (22) and b) mated cross-section (25)

24

Both flange sides in Figure 3.10 are identical. The orange part in between is the soft metal gasket.

A knife-edge that is machined below the flange’s flat surface provides the seal mechanism. As the

bolts are tightened, the knife edges make annular grooves on both sides of the copper gasket. The

extruded metal fills all the machining marks and surface defects in the flange, yielding a leak-tight

seal (24). Because the copper gasket gets deformed after the flanges impurities, it can be used

only one single time. It is not reusable, as was the case for the o-ring seal. Out of cost

consideration, some CF-flanges in the current setup at DMI are therefore equipped with o-rings

instead. The o-ring is placed inside the space for the gasket and the flanges are tightened by using

bolts in only half of the bolt-holes. This results in a connection that is only appropriate for high

vacuum, and hence this improper use of the flanges cannot be done in the new FERP-system.

CF-flanges are in general produced from stainless steel 304L or 316L. This type of steel does not

have residual magnetic properties, which could interfere with test results in most research

applications. This industry standard is also used at DMI; all flanges and other type of connections

are produced from these steel types. This requirement holds for all designs within this project.

3.3.3 Sizes and versions of CF-flange All pumps, gauges, chambers and other equipment in the future setup are connected using the CF

industry standard. CF flanges of different sizes need to be applied. In Figure 3.3 could for instance

be seen that the HiPace 80 Turbo-molecular pump is equipped with a CF flange. Figure 3.4b shows

a CF-connection on top of the ion pump. Based on the amount of bolts needed, it can be seen that

these flanges have different sizes. Because CF is an industry standard, the flange sizes are

standardized. Standard sizes are indicated by ‘DN - tube size’, shown in Table 3.1 (25).

Metric Inches Outer diameter

(mm)

Tube Inner diameter

(mm)

DN16 1-1/3 34 16

DN40 2-3/4 70 35

DN63 4-1/2 114 60

DN100 6 152 100

DN150 8 203 150

Table 3.1 – standardized CF-flange sizes

Besides different sizes, there are different versions of the CF-flange. Typically needed are

converter flanges, that convert one standard flange size to the other. Also exist the ‘diverse tube’-

version, which is a conversion of a larger flange size with a smaller tube inner diameter. Most used

variation on the standard flange is the rotatable flange. This flange can be rotated to align the bolt

holes before tightening. This property is very useful in a large setup where small misalignments

can easily occur. The rotating flange provides in this case a degree of freedom which ensures that

all parts can be connected exactly right. For this reason, all tubular connections in the future

vacuum setup need to feature at least one rotatable flange.


25

Most variations on the standard CF-flange are seen in the later design stage. Out of cost

consideration, DMI does not purchase flanges from manufacturers, but purchases stainless steel

304L or 316L disks that are machined down to a flange in the workshop. To this end, DMI uses a

standard handbook with technical drawings of all flange sizes and types (26). This handbook is

provided by LNLS, the Brazilian Synchotron Light Laboratory, a large facility that is also located in

Campinas. See http://lnls.cnpem.br/.

3.4 Other equipment With the vacuum pumps, gauges and flanges, a large part of the equipment is discussed. But these

parts are not nearly enough to build the complete system as desired by DMI. Other parts that are

required are discussed in this section. This concerns parts that have been newly purchased or that

were already present in the stock of DMI. Figure 3.11 shows a large order of parts that DMI

received from Kimball Physics during the internship period. Note: the red and yellow plastic covers

on the CF-connections function to protect the parts from dust and other contaminants.

Figure 3.11 – purchased parts that will be used for the future setup

3.4.1 Spheres

Up to this point the term ‘vacuum chamber’ was repeatedly mentioned. The main vacuum

chambers in the future setup are two spheres designed by Kimball Physics. These ‘spherical cubes’

are specifically designed to withstand the large external forces coming with vacuum applications.

With a CF-interfaces they are specified for UHV-application. One sphere was already part of the

old setup. This 4.5” (inches) diameter small sphere will function as the sample introduction

chamber in the future system. The larger 6” diameter sphere is newly purchased and will be the

main chamber in which the actual FERP-research takes place. The spheres in the new setup play an

important role in the design of the connections, and are therefore discussed in more detail in the

next chapter.

http://lnls.cnpem.br/

26

3.4.2 Viewport

Figure 3.11 shows a viewport top-center. This is a special type of flange, equipped with a glass

window of sufficient thickness. Elastomeric seals are used to attach the glass. The glass is

metalized and soldered, or fused with welding lips to compensate for the thermal expansion. This

way, a connection is made that is appropriate for UHV-application.

The new setup features two viewports, one on both spherical cubes. These viewports make sure

that the researcher can visually observe operations inside the system. In the main chamber must

for instance be checked whether the FERP sample plate (section 2.1) is positioned correctly.

3.4.3 Gate valves

Gate valves are used to (temporarily) separate parts of a vacuum setup. It is practically a doorway

that can be shut leak-tight, UHV specified. Gate valves come in many different forms and sizes.

They work either electro-pneumatically, electromagnetically or manually. The first two types are

ideal for automated vacuum processes. For the FERP-research at DMI however, the manual type is

preferred. Two manual valves with DN63 CF-connections by MDC vacuum are used. One of these

can be recognized top left in Figure 3.11. Possibly another, larger gate valve should be included in

the setup, this is discussed in section 4.3. The functioning of the gate valves becomes clear in the

procedure, section 5.2.

3.4.4 Transfer arm

A magnetic transfer arm is used to transfer the FERP-sample plate from the small sphere towards

the main chamber. Like gate valves, transfer arms come in many different forms and sizes, and

with different degrees of freedom to control. DMI purchased a 12” magnetic transporter by MDC

Vacuum, the long part on the left side of Figure 3.11. A simplified dimensional drawing is shown in

Figure 3.12.

Figure 3.12 – 12 inches magnetic transporter by MDC Vacuum (27)

This transfer arm is equipped with a DN40 CF-flange on the right end. The block on the left end of

Figure 3.12 can be translated and rotated and so does the sample inside the vacuum chamber,

using a magnetic connection. DMI uses this rotational DOF to grab or release the sample. A


27

specific sample holder is designed for this purpose, to which University of Twente student Tijmen

van Diepen contributed (28).

This transfer arm has a 12” raceway, However, if the stop clamp on the right side of Figure 3.12 is

removed, the translational DOF is extended to 16 inches. This turns out to be required in the later

design stage.

3.4.5 Residual Gas Analyzer The residual gas analyzer or RGA is a device that helps to identify the residual gases in a vacuum

system. While the gauges described in section 3.2 only provide an overall pressure, the RGA is able

to identify the contribution of partial pressures of different molecule species. This identification is

based on molecular masses and the mass-to-charge ratio. The RGA technology is not further

explained here, but extensive studies on the complex behavior can be found in literature (29). To

illustrate the use of it, Appendix B shows a plot that is obtained with the RGA for the current

research setup at DMI. Here it can be recognized that water is the most present contamination, a

factor 10 times more present than other species. Therefore, water is also playfully given the

nickname ‘great enemy’ by Vinicius L. Pimentel. A device that helps to remove water from the

vacuum chamber, is the TSP-Cryoshroud.

3.4.6 TSP Cyroshroud In earlier sections a TSP or Titanium Sublimation Pump was already mentioned. In the future

setup, the TSP is combined with a cryoshroud. The TSP-Cryoshroud is a standard combination

delivered by Gamma Vacuum, often used in combination with an ion pump (30).

The TSP is a small device that contains three titanium (Ti) filaments, see Figure 3.13a on the next

page. When used, a 50A current is put through a filament, which starts to evaporate. The Ti-vapor

reacts with contaminating gases (H2, CO) and water (H2O). The products from this chemical

reaction form a thin film on the inner surface of the vacuum chamber, covering the contamination

and the absorbed water. This process can only take up to 4 minutes, due to the high current and

the lifetime of the titanium filament.

The liquid cryoshroud consists of a thin-walled stainless steel cylinder with two feedthroughs, see

Figure 3.13b. The feedthroughs are used to fill the cylinder with cooling liquid. With cooling water,

the TSP pumping speed (for H2O) increases to 5,000 L/s. With liquid nitrogen, a pumping speed

(for H2O) of 20,000 L/s can be achieved. Hence, it is very useful to get rid of water molecules inside

the system. To compare, the TiTan Ion Pump (section 3.1.3) has a maximum pumping speed of

‘only’ 400 L/s for nitrogen (N2). Combining the ion pump and TSP-Cryoshroud allows for low

ultimate pressures in a short amount of time (30).

28

Figure 3.13 – a) TSP cartridge and b) liquid cryoshroud cylinder

Note that the TSP is placed inside the cryoshroud and hence much smaller, which can be

recognized based on the flange sizes in Figure 3.13. The cryoshroud is standard equipped with a

DN150 CF-flange. To include this device in the new research setup, a separate chamber is

designed. This is called the ‘crossing’, discussed in section 4.3.

3.5 Outgassing and bake-out In order to achieve and maintain the desired UHV-level of 5x10-12 Torr, the equipment needs to

be treated carefully. Parts must be specified for minimum release of gas molecules from the

surfaces into the system, called outgassing. A bake-out procedure can be used to significantly

increase outgassing before operation, which decreases pumping times (31). The amount of water

molecules that can desorb (type of gas molecules release) during operation is then minimized.

DMI wants to apply a bake-out temperature of 150 °C for the new FERP-system. Figure 3.14 shows

the ‘oven’-setup that is used for a bake-out.

Also, the walls can be cleaned by the use of plasmas, by putting an electric current through the

low pressure environment. Contamination on the chamber walls can beforehand be minimized by

the use of gloves while handling vacuum equipment.

Figure 3.14 – setup for bake-out of STM system in Belo Horizonte


29

4 Design Now all commercial vacuum equipment for the new setup is discussed in the previous chapter,

design of the required parts to complete this setup can be carried out.

4.1 From quick concept to final design During his internship at CTI in 2014, Jildert Anema made a quick concept of a new research setup

(1). This concept functioned to acquire the required budget to buy necessary commercial parts.

DMI received the budget and purchased this equipment. However, some changes have been made

to the quick concept. A new CAD-model is therefore desired. This model should include the

changes that are made and provides detail for the parts that still need to be designed. This means

that all connections between the commercial parts need to be detailed up to the level that they

can be manufactured by the workshop. The end product of this internship for the detailed final

setup is therefore a complete CAD-model with technical drawings of all the parts to be

manufactured. Figure 4.1 shows the initial quick concept by Jildert Anema.

Figure 4.1 – front view of CAD-model of (initial) quick concept (1)

All yellow colored parts in Figure 4.1 need a detailed design for manufacturing. The most

important (re)designs are summarized in Table 4.1, the numbers correspond to the numbers in the

figure.

30

# Part Description

64 Crossing A detailed redesign of the crossing is needed,

described in section 4.3. Note that this is the chamber

for the TSP-Cryoshroud.

65 Conversion nipple crossing to

main chamber

Due to the redesign of the crossing, a new DN150 to

DN100 conversion nipple towards the main chamber is

needed in this location. This detailed design is

described in section 4.4.1.

8, 41 Nipples small sphere to main

chamber

Detailed designs are needed for a DN63 to DN63

nipple between the small sphere and the gate valve

and a DN63 to DN100 nipple between the gate valve

and the main chamber. Described in section 4.4.2.

- Nipples small sphere to turbo-

molecular pump

Detailed designs are needed for two DN63 to DN63

nipples between the small sphere, gate valve and

turbo-molecular pump, described in section 4.4.3. Not

visible in the figure, location is on the backside of the

small sphere.

46 Top flange of main chamber Detailed design of this top flange is needed, to easily

place FERP-head on main chamber in the future.

Discussed in section 4.5.

Table 4.1 – required (re)designs

The yellow colored parts that are not mentioned in the table, are CF Flanges that can be

manufactured by the workshop using the LNLS handbook (26). Furthermore, minor adjustments to

the CAD-model are needed. The large two-stage ion pump on the bottom in Figure 4.1 is replaced

by the Gamma Vacuum TiTan 400L. And possibly, a large gate valve will be placed between the

crossing and the ion pump (location 78) in the future. This is discussed at the crossing design in

section 4.3.

4.2 Requirements In the foregoing chapters it was seen that design for vacuum systems is mostly limited to

standardized equipment based on standard vacuum requirements. Besides these standard

requirements, CTI has demands that make the final setup achievable. For instance, based on costs

and available production methods. Table 4.2 summarizes the requirements for designs in

upcoming sections, based on the conclusions from foregoing information.


31

1. For all metal parts, the material to be used is stainless steel 304 or 316L. This steel type

does not have residual magnetic properties that could affect research results.

2. The dimensions of each part should be as such that easy assembly within the complete

setup is guaranteed.

3. All tubular connections should at least contain one rotatable flange. This degree of

freedom is needed for easy assembly of a large configuration.

4. Parts need to be produced at CTI workshop or LNLS workshop, machining processes are

therefore limited to milling, turning and laser cutting. In certain cases, an external

manufacturer may be invoked, known by DMI.

5. All CF-Flanges are manufactured following the LNLS handbook (26), tolerances from this

handbook need to be used.

6. All production costs should be kept as low as possible. There is no budget available, this

needs to be acquired based on the designs.

7. All parts need to be able to withstand temperature up to 150°C, which is the temperature

used in the bake procedure.

8. The conductance (not mentioned before in this report) of a part should be kept as high as

possible. This means for tubes that short lengths and large diameters are demanded. In

practice these diameters are determined by the flange sizes of commercial equipment.

Table 4.2 – requirements for designs for new vacuum setup

4.3 Crossing The first part to be (re)designed is the crossing between the main chamber and the ion pump. This

crossing is used to place the TSP-Cryoshroud, explained in Section 3.5.6. The initial design of Jildert

Anema (part 64 in Figure 4.1) was based on the DN100 connection towards the main chamber on

top. It was made such that the cryoshroud was not blocking the air flow from the main chamber

towards the ion pump, clearly shown in Figure 4.2. This resulted in an asymmetric design, with

weight concentrated on the right side of the crossing.

Figure 4.2 – exploded view and entry of cryoshroud in intitial crossing design

32

The idea of making an asymmetric part because of the airflow is not needed. The TSP-Cryoshroud

may partly block the flow from the main chamber, although this seems bad for conductance on

first hand. It would badly affect the flow in the viscous flow regime, but not in UHV, which is

present in this part of the setup. Only a gap is needed, sufficient for molecules to pass towards the

inlet of the ion pump below. It is possible to make the crossing symmetric, which is preferred for

the ease of production and assembly.

Besides making the crossing symmetrical, another adaption is needed. Because of the possible

placement of a large DN150 gate valve (Figure 4.3) on top of the ion pump in the future, the

DN100 CF-flanges of the crossing need to be replaced by DN150 versions. This gate valve should

protect the ion pump from contamination by particles from other locations in the system, when

these are in higher pressure levels. This is an idea for the future, because bake resistant large gate

valves are commercially available, but expensive. DMI currently lacks the budget to buy a

$4.365,00 large gate valve, as the DN150 version by MDC Vacuum.

Figure 4.3 – DN150 gate valve by MDC vacuum

Note that with this redesign a DN100-DN150 conversion nipple towards the ion pump (or gate

valve) is not needed anymore. However, a DN150-DN100 conversion is now needed on the other

side, towards the main chamber on top. This design is discussed in section 4.4.1. If the large gate

valve will be purchased, is still up for discussion. Nevertheless, it is chosen to provide the crossing

with four DN150 connections, because this results two-way symmetrical design.

4.3.1 New crossing design

The adjustments to the initial crossing design are rather simple. The TSP-Cryoshroud is moved

towards the center and the DN100 CF-flanges are replaced by DN150 versions. This means that the

tube size and conductance increase. The redesign is carried out stepwise, as described below.

Initially the width and the height of the tube design are kept the same with respectively 355 mm

and 221 mm. The vertical tube is transformed into the DN150 version and is moved towards the

center. Figure 4.4 illustrates how much space is left for the air flow.


33

Figure 4.4 – first changes to old design and leftover airflow space

There is enough space for molecular flow towards the ion pump, but immediately it can be seen

that a problem arises with the assembly of this design. This problem occurs with the bolts for the

top and bottom flange. The bolts that are used to fix the DN150 bottom flange of the crossing to

the DN150 top flange of the ion pump have a length of 60 mm including the head. The height of

the crossing must therefore be adjusted, to leave enough space for easy placement of these bolts

(requirement 2). Furthermore, the width can be reduced to save material and weight. The gap for

the air flow left can be minimized. The following step concerns extension of the height and

reduction of the width.

To make these changes easily, a CAD-model of the bolt is made in SolidWorks. In the CAD-model of

the crossing, this bolt is placed where the distance between the bolt hole of the flange and the

tube is minimal. The distance required here, defines the new height of the crossing: 317 mm

including the two CF-flanges. In the assembly process a CF-flange is placed around the tube and

then welded. The amount of tube that enters the DN150 flange is 9.5 mm. The total tube height

then becomes 292 mm. This is clarified in the production of the crossing, section 4.3.2.

At this point, it would be convenient to produce a two-way symmetric crossing. In that case, it

would not matter how the crossing is assembled in the complete research setup, which leaves less

chance of error. The tube’s width is therefore reduced to the dimension of 292 mm. Figure 4.5

illustrates the leftover space for the air flow, which is the other important design parameter.

Figure 4.5 – leftover space for air flow towards ion pump

34

The gas molecules only need a very small space to pass towards the ion pump, according to

Vinicius L. Pimentel. In practice, the ion pump will be activated during a few days, before an actual

FERP-experiment. It slowly removes particles from inside the system. This is a statistical process,

as explained in section 3.1.3. The gap in Figure 4.5 could for that reason be reduced even further,

but this is not done. With sufficient space for the passage of particles inside, sufficient space for

the placement of the required bolts on the outside and a two-way symmetric design for the ease

of production and assembly, this is the optimal crossing design for this application.

4.3.2 Crossing part dimensions and production

The new crossing basically consists of 5 parts: 1 tubular part and 4 DN150 flanges. The way they

are produced is shortly discussed here.

Tubular part

The exact dimensions of the tube depend on the connection to the flanges and the space required

for placement of the bolts. The tube height and width are determined to be 292 mm. The flanges

are welded onto the tube. To this end, the tube enters the flange a little distance. This is a

standard way to connect tubes and flanges in vacuum applications.

This dimension can be recognized in the technical drawing of a DN150 flange in Figure 4.6. The

tube enters from the bottom. The 9,5 mm dimension is of importance here. This is part where the

tube enters the flange. A weld is made in the corner at the end of this 9,5 mm track, to fix the

flange to the tube.

Note that the knife-edge of the flange is on top in Figure 4.6. This is where the copper gasket is

placed for the connection to another flange.

Figure 4.6 – technical drawing of the cross section of a DN150 CF-flange (26)

The tube size is dependent on the external manufacturer. Appendix C shows the standard sizes of

the materials supplier for DMI. It can be seen that in case of a DN150 configuration, a tube with an

outer diameter of 152,1 mm is delivered. One might recognize that this tube size fits within the

153 mm diameter of the flange seen in Figure 4.6. For a two-symmetric design with the bolt

lengths of 60 mm, it can be concluded that the following height and width are needed:

2 ∗ 60 𝑚𝑚 (𝑏𝑜𝑙𝑡𝑠) + 2 ∗ 9,5 𝑚𝑚 (𝑤𝑒𝑙𝑑) + 152,1 𝑚𝑚(𝑡𝑢𝑏𝑒 𝑂. 𝐷. ) = 291,1 𝑚𝑚


35

This dimension is rounded up to 292 mm. This finding supports the dimension found with the CAD-

models in the previous section. One might say that the margin of 0.45 mm on both sides to place

the bolts is small. However, the bolts can be placed easily under a small angle. It might also be

expected that the use of a weld between the tube and the flange increases the height a bit. But

according to Vinicius L. Pimentel, based on experience, the resulting change in dimension can be

neglected.

The final tube design has a width and height of 292 mm. The tubes have a standard other diameter

of 152.1 mm and an inner diameter of 148.1 mm. The wall thickness is 2 mm. The design is shown

in Figure 4.7.

Figure 4.7 – design of the tube

Appendix D contains a detailed technical drawing of the tube design. This can be used to

manufacture the part.

Manufacturing of the crossing needs to be precise. The seams must be leak-tight with the UHV-

application. According to Vinicius L. Pimentel, the external manufacturer and supplier of the

required parts, has made this kind of structures in the past using a specific manufacturing process.

With a specialized drill, a hole is made in a tube, by which the tube material is extruded along the

drill. Another tube can then be welded onto the tubular extrusion that is made. The question is

whether this process works for the crossing, in which both tubes have the same diameter. The

required manufacturing process is therefore left to the experience and insight of the external

manufacturer, and not further discussed here. The type of connection that needs to be

manufactured, can be recognized in Figure 4.8 below.

Flanges

A total of 4 DN150 CF-flanges is needed to complete the crossing design. Two types are needed,

twice a standard version and twice a rotatable version. In the LNLS handbook (26) these different

types are indicated by CF150PD (Padrão) and CF150RR (Rotativa). This is also how they are

mentioned in the technical drawings in Appendix D. To show the function of the rotatable flanges

practice here: if for instance on the top and bottom of the crossing ´fixed´ CF150PD flanges would

36

be used, small misalignments between the holes of the ion pump (or gate valve) on the bottom

and the nipple towards the main chamber on top would cause problems. It would result in

undesirable or even impossible placement of the parts. A small misalignment in the start of the

assembly, can result in large misalignments in other parts. To be able to assemble the complete

setup as desired, rotatable flanges are applied. These ‘rotary flanges’ consist of a fixed part and

rotatable part. The fixed part contains the knife and is welded onto the tube. The rotatable part

contains the bolt holes and can move freely around the tube. Figure 4.8 shows the fixed and

rotatable parts of a rotary flange on another piece of equipment in the laboratory of DMI.

Figure 4.8 – fixed and rotatable part of a rotary flange

For the production of the flanges, DMI receives raw material. For each flange a stainless steel 316L

solid disk is required. In case of the DN150 flanges, this disk should at least have a thickness of 22

mm, see Figure 4.6. In the workshop at CTI, the disk is then formed into a flange by applying

turning and milling, following the designs of the LNLS handbook.

Assembly of crossing

When all five parts are manufactured, the crossing can be assembled. To this end, the two

CF150PD flanges and the fixed parts of the CF150RR flanges are welded to the 4 ends of the tube.

Special attention need to be paid to the assembly of the rotary flanges. The rotatable part must

first be placed, before welding the fixed part to the tube. Otherwise the rotatable part cannot be

placed anymore and the flange needs to be disassembled. This problem might be recognized by

thinking of how the flange in Figure 4.8 was placed. Figure 4.9 on the next page shows the new

crossing design with its exploded view. The rotary flanges consisting of two parts can be clearly

distinguished here. Appendix D contains the technical drawing of the assembly, providing the level

of detail required.


37

Figure 4.9 – new crossing design and exploded view

4.4 Nipples The connections between the purchased commercial parts need to be realized. These connections

are called ‘nipples’ in vacuum technology. A nipple basically consists of a tube and two flanges,

used to connect to other vacuum parts. As an example, Figure 4.11 shows a typical nipple from a

research setup at the LNLS laboratory. This nipple forms a connection between a sphere and a

gate valve.

Figure 4.11 – Typical nipple in setup at LNLS

The nipple has large dimensions, providing enough space for fixing the bolts on the CF-flanges on

both sides. This is desirable. It will be seen that with the nipple designs for the new setup at DMI

however, this is unfortunately not always that simple. The figure above shows a standard DN100

to DN100 connection. Off course there are also conversions from smaller to larger flanges. This is

for instance seen for the first nipple to be designed, between the crossing and the main chamber.

38

4.4.1 Nipple between main chamber and crossing

The first nipple design to be addressed is the one from the main chamber towards the crossing. It

was mentioned in section 4.3 that a DN150 to DN100 conversion is needed here. There are no

difficult requirements for this design, apart from the fact that (again) the bolts need to be placed

easily. The basic design consists of a DN100 flange to a DN150 flange, with a DN100 tube in

between.

Because of the two different flanges, two different types of bolts are needed. The connection

towards the crossing is made using the 60 mm bolt mentioned in the previous section. This bolt

goes entirely through the holes of the nipple and the crossing, to be tightened by a nut on the

other side of the flange. The second type of bolts is needed for the connection to the main

chamber. Here, a 39.3 mm silver plated bolt is used. This length is including the bolt head. These

bolts are specified for the large sphere produced by Kimball Physics, and have therefore a thread

that is dimensioned in inches. The spheres feature threaded holes in which the bolts can be fixed,

another connection type than is seen at the side of the crossing. For clarity, both connection types

are shown in Figure 4.12.

Figure 4.12 – two types of bolt connections, tapped holes and through-holes with nut

Figure 4.13 shows schematically the basic design of the needed nipple. The figure reveals that

there is enough space around the CF100 flange to place the 60 mm bolts easily, which is later

verified in the CAD-model of the complete setup. The distance between both flanges is

determined by the length of the small bolt with its 39,3 mm in total.

For the nipple design, this distance is chosen to be 42 mm. Then there is a margin of 42 - 39.3 = 2.7

mm to easily place the bolts. The tube enters the DN100 flange for 9 mm and the DN150 flange for

9.5 mm, which means a tube length of 60.5 mm is needed. The DN100 flange is chosen to be the

necessary rotatable CF100RR version, because this is the smaller flange. The DN150 flange is a

CF150TD ´Tubos Diversos´ version. This name is given in the LNLS handbook for flanges with a

smaller tube size (and thus hole) than corresponds to the flange size. In this case a DN150 flange

with a DN100 tube or hole size.


39

Figure 4.13 – schematic view of nipple design between crossing and main chamber

The final design and exploded view are shown in Figure 4.14. The total height of the nipple is 84

mm, with the flange thicknesses of 20 (DN100) and 22 mm (DN150). Technical drawings can again

be found in Appendix D. It can be concluded that this first nipple design was very straightforward.

Figure 4.14 – first nipple design with exploded view

The production of nipples is also rather easy. Whereas the tubular part for the crossing in section

4.3 is difficult to produce, the tube here is plain and simple. The tubes for DN63 are standardized,

see the Appendix C. The tubes are purchased with standard diameters and cut in the correct

length. The flanges are produced by turning and milling of the blank AISI 316L steel disks. In the

end, all parts are welded together, except for the free parts of the rotary flanges. Again, the order

of assembly is of crucial importance here. The rotatable part of the rotary flange should be placed

around the tube before welding the fixed part. If a mistake is made here, a complete new nipple

must be manufactured.

4.4.2 Nipples between small sphere and main chamber The most important nipples for the new system to work, are those between the small sphere, the

small gate valve and the main chamber, numbers 8 and 41 in Figure 4.1. These designs are closely

40

related by space limitations. The maximum length depends on the FERP-sample transfer, whereas

the minimum nipple size is yet again determined by the space needed to fix the bolts.

It was explained in section 3.4.4 that the extended reach of the transfer arm is limited to 16

inches. This is where this DOF comes to use. The magnetic transfer arm is used to transfer the

sample from the pre-vacuum chamber (small sphere) to the main chamber. The specified sample

holder is placed on the end of this transfer arm. As a start, the sample is located in the perfect

center of the small spherical cube. From this position, once the vacuum is at desired level, the

sample is transferred through the first (to be designed) nipple, the small gate valve and the second

nipple, towards the main chamber. This distance is thus limited to the 16 inches’ reach of the

transfer arm. The dimensions of the gate valve and both spherical cubes are known, the combined

length of the nipples needs to be limited. Figure 4.15 illustrates the leftover design space.

Figure 4.15 – available space for design of nipples

16” = 406.6 mm. The radius of the small spherical cube is 62 mm. The radius of the main chamber

is 106,4 mm. The width of the small gate valve is 70,1 mm. Hence, the leftover design space for

the two nipples is:

406.6 𝑚𝑚 − 106.4 𝑚𝑚 − 70.1 𝑚𝑚 − 62 𝑚𝑚 = 168.1 𝑚𝑚

Now the maximum dimensions are known. The minimum length of the nipple designs is limited by

the bolts. The gate valve and the two spheres are from different manufactures (MDC Vacuum and

Kimball Physics) that apply different units in their designs. While the bolt holes of the valve are

dimensioned in mm’s, the bolt holes of the spheres are dimensioned in inches, as seen with the

previous nipple design. Two different kinds of bolts are therefore needed. The connections here

are DN63 on the small sphere and valve and DN100 on the main chamber. Although there is a

difference in flange size for both spheres, the same bolt is used at these connections. Both needed


41

inches- and mm-dimensioned bolts are shown in Table 4.3. With the maximum length and applied

bolts known, the nipple designs can now be detailed.

Silver plated bolts (thread in inches)

Used in spherical cubes threaded holes

Standard bolts (thread in mm)

Used in gate valve threaded holes

Thread length: 1 ¼” = 31,75 mm

Head length: 7.6 mm

Total length: 39.3 mm

Thread length: 29,5 mm

Head length: 5.6 mm

Total length: 35.1 mm

Table 4.3 – applied bolts

Design nipple 1: Small sphere to gate valve

The first nipple is the connection between the small sphere and the gate valve. The standard

design of this nipple consists again of two flanges and a tube. The flanges are in this case a

standard DN63 and a rotatable DN63, as required for alignment.

This nipple must be designed as short as possible. The distance between the two flanges must

therefore be minimized. The minimum distance is equal to the bolt length. The alignment of the

bolt holes matters here, as clearly indicated in Figure 4.16.

Figure 4.16 – difference holes aligned or not

From Figure 4.16 it can be easily concluded that the shortest nipple can be manufactured in the

case that the bolt holes are not aligned. But this must be possible dependent on the bolt

alignment of the gate valve and the spheres in the setup. Fortunately, the engineers of Kimball

42

Physics did already put their thoughts on this opportunity. Their spherical cubes feature twice as

many threaded holes as needed for the CF-connection. In case of the small 4.5” sphere, there are

16 holes instead of the 8 that a normal DN63 CF-flange features, see Figure 4.17.

Figure 4.17 – twice as many bolt holes on spherical cube (16 instead of needed 8 for DN63

connection)

This convenient design aspect has the result that the bolt holes of both flanges of the nipple can

be shifted in relation to each other. In case of the DN63 flanges, the bolt holes (or flanges) can be

rotated an angle of 22°30´ relatively to each other. Use of one rotatable CF63RR flange on the

nipple, makes this easy. The flanges do not have to be fixed in the angle of 22°30´ in relation to

each other, but this configuration can be guaranteed on the moment that the CF63RR is mounted

onto the sphere or the gate valve, depending on the desired way of assembly.

In the desired final configuration of DMI, the small gate valve is placed in upright position. This

way, the manual control of the valve can be carried out in the easiest way. The bolt hole locations

of the gate valve in upright position can be recognized in Figure 4.18. Hence, on the small sphere

the holes in between are used, which results in the convenient nipple configuration of Figure

4.16b. Note that if you look closely at the nipple-design of the LNLS setup in Figure 4.11, you can

see that the bolt holes of the flanges are also not aligned.

Figure 4.18 – hole configuration gate valve in upright position (MDC small gate valve)

The distance between the two flanges needs to be at least the total length of the silver plated

bolts: 39.3 mm. With the 17.5 mm thickness of two DN63 flanges added, the total nipple length

becomes:


43

17.5 𝑚𝑚 (𝐷𝑁63) ∙ 2 + 39.3 𝑚𝑚 (𝑏𝑜𝑙𝑡) = 74.3 𝑚𝑚

This length is less than half of the available space of 168.1 mm. It seems reasonable that with the

design of both nipples the total length stays within this limit. However, the second nipple is

different: a conversion from DN63 to DN100, similar as the design seen in the previous section.

Design nipple 2: gate valve to main chamber

The second nipple is located between the gate valve and the main chamber. A DN63 to DN100

connection is needed here, because of the DN100 interface of the main chamber. As said, this

DN100 size does not make a difference for the applied bolts. The 39.3 mm, silver-plated, inches-

dimensioned bolts from Table 4.3 are to be used here. On the gate valve side, the mm-

dimensioned bolts with a total length of 35.1 mm are used again.

Figure 4.19 shows the convenience occurring with the CF63-to-CF100 conversion. The space

around the CF63 flange is sufficient to move the 39.3 mm bolts freely towards the holes on the

CF100 flange. This means that the distance between both flanges only needs to be large enough

for the smaller mm-dimensioned bolt. This convenience was seen with the first nipple design in

section 4.4.1, but now clearly indicated in the CAD-model.

Figure 4.19 – bolt placement on DN63-DN100 nipple

Figure 4.19 shows the simplest design possible, for which the dimension can be determined right

away. The distance between both flanges is minimally 35.1 mm, the small bolt length. The DN63

flange has a thickness of 17.5 mm, the DN100 flange 20 mm (26). The total nipple length is

therefore:

17.5 𝑚𝑚 (𝐷𝑁63) + 20.0 𝑚𝑚 (𝐷𝑁100) + 35.1 𝑚𝑚 (𝑏𝑜𝑙𝑡) = 72.6 𝑚𝑚

The minimum required space for both nipple designs is now known. Note that tolerances for easy

placement of the bolts are added afterwards. The minimum required space is:

168.1 𝑚𝑚 − 74.3 𝑚𝑚 (𝑛𝑖𝑝𝑝𝑙𝑒 1) − 72.6 𝑚𝑚 (𝑛𝑖𝑝𝑝𝑙𝑒 2) = 21.2 𝑚𝑚

44

This margin of 21.2 mm provides space for required tolerances. The first nipple designs and

needed parts can now be detailed.

Parts and production

Both nipples of this section consist of two flanges and a tube. As required, for both designs one of

the flanges is a rotatable flange. The dimensions of the tubes are now to be determined. As was

seen with the previous designs, on both sides the tube partly enters the flanges, to be welded to a

corner inside.

In case of the first nipple, a CF63PD and CF63RR are used. The tube enters these flanges over a

distance of 7.5 mm. It must be noted that this dimension is the same for both the fixed and the

rotary flange, although the last one consists of two parts. The minimum nipple length is 74.3 mm.

This is rounded up to 76 mm, to provide space for placement of the bolts. This means that the

distance between both flanges is 76 – 17.5 * 2 = 41 mm. The required tube length is therefore 41 +

2 * 7.5 = 56 mm. Figure 4.20 shows the exploded view of the first nipple. Appendix D contains the

technical drawing used for production.

Figure 4.20 – exploded view first nipple

The second nipple contains the Tubos Diversos version of DN100 flange with a DN63 tube. The

cross section of this flange is shown in Figure 4.21 on the next page.

Figure 4.21 – CF100TD cross section


45

The tube enters from below. In case of the CF63 tube, the bottom part of the circular cut in the

flange has a diameter 60.5 mm. The tube enters this flange for 9 mm, to be welded in the corner

where the circular cut is made smaller.

On the other side of the tube a DN63 rotatable flange is placed. According to Vinicius L. Pimentel,

the most convenient option is to make the smallest flange into the needed rotatable version. The

tube enters this flange over a distance of 7.5 mm. The minimum total nipple length was 72.6 mm,

which is rounded up to 75 mm for easy placement of the bolts. This means that the distance

between both flanges is 75 – 20 – 17.5 = 37.5 mm. The tube length is 37.5 + 9 + 7.5 = 54 mm.

Figure 4.22 shows the exploded view for the second nipple. The larger DN100 flange can be clearly

distinguished on the left. Appendix D contains the technical drawing for production.

Figure 4.22 – exploded view second nipple

The leftover space is determined with the final dimensions known:

168.1 𝑚𝑚 − 76 𝑚𝑚 (𝑛𝑖𝑝𝑝𝑙𝑒 1) − 75 𝑚𝑚 (𝑛𝑖𝑝𝑝𝑙𝑒 2) = 17.1 𝑚𝑚

There is 17.1 mm design space left. Sample transfer with the magnetic transfer arm can easily

succeed. Figure 4.23 shows the space available to place the small 35.1 mm bolts, in the final

design.

Figure 4.23 – available space for placing bolts

46

Methods to further reduce the nipple length

In the quick CAD-concept of Jildert Anema the distance between both sphere centers was set to

334.5 mm. This section showed that it is impossible to fix the bolts if this dimension would be

used, because a minimum distance of 406.6 – 17.1 = 389.5 mm is needed. However, there are

possibilities to reduce this length further. This can for instance be done by already placing the

bolts in the flange during the manufacturing process of the nipple. But this would mean that the

bolts cannot be replaced, which would result in a badly maintainable or not-reusable nipple, which

is not desired by DMI.

Another option was reviewed at the start of this project, because it was temporarily unclear what

types of bolts would be used. At this time, it is clear that bolts of 39,3 mm are used, but in the

beginning the designs were made for smaller bolts of 31 mm length. At that moment the concept

of Figure 4.24 was designed. In this concept cuts around the bolt holes make it possible to slide

the bolts within position. Cuts of 5 mm depth on the DN63 flanges were used, which resulted in a

total distance between both sphere centers of: 64 + 61 + 70,1 + 106,4 + 62 = 363.5 mm. This was

enough at the time for the bolts used, but more than the initial 12” (304.8 mm) length of the

transfer arm. It can be concluded that the transfer arm needs to be extended to 16”, as also

acknowledged in the quick concept. Furthermore, for the ease of manufacturing, the simplest

concepts as described before are used. Kimball Physics produces close couplers for this type of

limited-distance application (32), but these products are too expensive for use in the FERP-system

of DMI.

Figure 4.24 – initial concept for reduction of nipple length

4.4.3 Nipples between small sphere and turbo-molecular pump

The last two nipples to be detailed are those that connect the small sphere to the turbo-molecular

pump. This part of the setup is not visible in Figure 4.1, but can be clearly explained. A DN63 to

DN63 nipple is needed between the small sphere and the gate valve. Then another DN63 to DN63

nipple is placed between the gate valve and HiPace 80 turbo-molecular pump. The gate valve is


47

used here to be able to open the sphere while the pump is still running. This ensures that the

pump does not experience harmful atmospheric pressure. The shutdown time of the pump may

take up to 20 minutes. By applying a gate valve, the required time to replace a FERP-sample can

therefore be greatly reduced.

In the quick concept the turbo-molecular pump was directly connected to the gate valve. The

HiPace 80 has grooves that enable this kind of connection, as can be recognized in Figure 3.3. For

the final design however, a nipple is preferred at the inlet of the turbo-molecular pump. This

makes it easier to connect the valve and the pump and is preferable for balancing the pressures on

opening the valve. Hence, two DN63 to DN63 nipples are used.

In section 4.4.2 already a DN63-DN63 nipple was designed. This design made use of a shifted hole

configuration, to reduce length. This principle can also be applied here, because the sphere

features twice the amount of required holes, the gate valve is again placed in upright position and

the turbo-molecular pump can be mounted in any desired direction. The length of the nipple

between the valve and the pump could even be further reduced, because smaller bolts are used

here. Although this is a bit preferable for conductance, the ease of production is of greater value.

Hence, for the two nipple designs between the small sphere and the turbo-molecular pump, the

DN63-DN63 nipple design of section 4.4.2 is re-used. This means that this type must be produced

three times, which is an easy task for the workshop.

It was seen that the design of the nipples was repeatedly a similar task. Only small adjustments to

dimensions were needed to be made, which was very straightforward. Table 4.4 summarizes the

nipple designs made in section 4.4.

Nipple Flange sizes Total length (mm)

Main chamber to crossing DN100-DN150 84

Small sphere to gate valve DN63-DN63 76

Gate valve to main chamber DN63-DN100 75

Small sphere to gate valve DN63-DN63 76

Gate valve to turbo-molecular pump DN63-DN63 76

Table 4.4 – all nipple designs

48

4.5 Top flange for main chamber The last part to be designed is the top flange for the main chamber, location 46 in Figure 4.1. Here

the FERP-head must be placed inside the main chamber. The head is the device with all the

elements and wires needed for the FERP-research, see section 2.1. The head on top of the current

research setup is shown in Figure 4.25a. The head is mounted on a DN63 flange. The main

chamber has a DN100 interface. This means that a special kind of flange is required, a so-called

‘Dupla Face’ (Double-Faced): a DN100 flange that features tapped holes on which the DN63 flange

of the FERP-head can be mounted. The standard tolerances of the LNLS handbook (26) are used to

provide the design of this flange.

The goal of the top-flange is easy placement of FERP-head and all wires and feedthroughs that are

needed. To this end, the center hole size must be as large as possible. This dimension is limited by

the inner diameter of the DN63 copper gasket, that is used as the seal between the double-faced

flange and the DN63 flange of the FERP-head. This diameter is 64 mm. With the standard

dimensions of LNLS and the maximum inner diameter, the top flange design can be completed. Its

design is shown in Figure 4.25b and the technical drawing can be found in Appendix D.

Figure 4.25 – a) DN63 connection on old setup and b) new DN100-top flange for main chamber

A few remarks can be made about this design. At this moment, two gaskets are used: a DN100

gasket between the sphere and the first flange, and a DN63 between the first flange and the FERP-

head. In the future, it might be preferable to equip the FERP-head with a DN100 flange, such that

it can be mounted directly onto the main chamber.

Furthermore, the design of the flange could be further optimized by chamfering the bottom edge

of the center hole. If a large chamfer is made here, parts could be placed even more easily inside

the chamber. This consideration is made on the end of the internship and left to DMI.


49

5 Assembly With all the required equipment discussed in chapter 3 and all the designs completed in chapter 4,

the new system can now be assembled. As stated in the introduction, there is no budget available

to produce the designed parts, this is why the final product does not yet exist in reality. A CAD-

model of the complete setup is made in SolidWorks 2014. This model functions as a guide for

assembly. Furthermore, this is the extension on the initial CAD-models produced by Jildert Anema

during his internship at CTI in 2014 (1).

5.1 CAD-model of complete setup Figure 5.1 shows the CAD-model of the complete setup produced in SolidWorks 2014. The colors

are used to indicate the status of a part, see the legend.

Figure 5.1 – CAD-model of complete setup (CHANGE, adapted nipples)

50

The red parts are those that are already present in the laboratory of DMI, for instance the pumps,

magnetic transporter and spheres. The green parts are the ones that need to be manufactured by

the workshop. This contains the designs from previous chapter and additional flanges. For

instance, the DN150 blank flange on bottom of the ion pump, the DN63 blank flanges on the main

chamber and a DN63-DN40 double-faced flange between the small sphere and the transfer arm.

Note the customized top flange on the main chamber for placement of the FERP-head, described

in section 4.6. There is one yellow part in the figure, a DN63 gate valve. This valve is similar to the

one that is already used between both spheres. The yellow color indicates that this part still needs

to be purchased.

Another part that could be purchased, is the DN150 gate valve between the crossing and main

chamber. However, the researchers at DMI are discussing whether this part is needed. The ion

pump can be switched on and off. According to Marcos Hamanaka, the larger and expensive gate

valve would therefore only provide unnecessary protection for the ion pump, which is not worth

the expenses.

Other parts that are missing in the CAD-model of Figure 5.1 are the diaphragm pump and all

gauges, because no models were available. Remember that a Pirani and combination gauge are

placed on the small sphere and a Pirani and Bayard-Alpert gauge are placed on the main chamber.

The diaphragm pump is placed in sequence with the HiPace turbo-molecular pump. For the

simplicity of the model, all bolts and gaskets are also left out in this CAD configuration.

5.2 Procedure before FERP-experiment With the help of Figure 5.1, the required sequence of steps before a FERP-experiment can now

shortly be listed:

1. Pumping the complete system down to HV-UHV using diaphragm and turbo-molecular

pump

2. Close the gate valve between main chamber and small sphere and slowly pump in

nitrogen to increase pressure in small sphere to atmospheric pressure again

3. Open blank flange in front of small sphere and place FERP-sample on sample holder, then

close sphere again and pump pressure down to same level as in main chamber.

4. Open gate valve between main chamber and small sphere, use magnetic transfer arm to

place sample on the FERP-head (not shown in the figure), retract transfer arm and close

gate valve.

5. Use Ion Pump and temporarily the TSP-Cryoshroud to reduce pressure in main chamber to

5x10-12 Torr, this process may take several days according to Vinicius L. Pimentel.

6. Start FERP-experiment when desired pressure in main chamber is achieved. See section

2.1.

Furthermore, a bake-out procedure and system cleaning using plasmas are applied before all

these steps are carried out. The bake procedure is used to get rid of water in main chamber. The

total procedure should make clear why the UHV-setup is constructed like shown in the CAD-


51

model. The function of the small gate valve towards the turbo-molecular pump is explained in

section 4.4.3.

Note regarding step 6, that single atom tip (cathode) is already present on FERP-head. The main

chamber needs to be opened to replace this tip, which is ineffective. A redesign of the FERP-head

and sample holder is therefore desired, to replace the cathode together with the sample plate.

This might be a challenging assignment for future interns. This redesign is not discussed further in

this report.

5.3 System weight and support structure The new setup needs to be placed somewhere in the DMI laboratory. To this end, a support

structure needs to be provided, preferably one that can be moved. Out of cost-consideration, a

support is constructed from a setup that is already present in the laboratory.

5.3.1 List of system components and weight

The mass of complete system is determined; this is of interest for the required support. It must be

noted that this is just presented as an indication. The support is already present in the laboratory

of DMI and no structural calculations are carried to indicate whether this support will indeed

suffice. The weight of commercial parts is retrieved from datasheets. The weight of designed parts

is determined by retrieving their volumes from SolidWorks. These values are multiplied by the

specific weight of the used stainless steel AISI 304, which is has a mass density of 8000 kg m-3 (33).

All parts and corresponding masses are shown in Table 5.1 on the next page.

Note that the masses for the flanges are also estimated using SolidWorks, because the LNLS

Handbook (26) does not provide this information. With all weights added in the table, a total

weight of about 181 kg is assumed for the complete system. The weight for bolts and nuts is

estimated and the weight computation by SolidWorks is an approximation. The calculated value is

for that reason an indication rather than an exact prediction of the total weight. If the large gate

valve would be added as protection for the ion pump, an approximate weight of 16.8 kg must be

added (MDC 300018).

5.3.2 Support structure

With the system dimensions and weight known, the support structure can be provided. DMI wants

to make use of a rack that is already present in the laboratory, shown in Figure 5.2a (page 53). This

rack is a table from which the top can be removed. The CAD-model is used to confirm that the

FERP-system fits on this rack. See Figure 5.2b. From this figure it is clear that a bridge needs to be

created between the two long bars on the bottom, on location A in the figure. Furthermore, the

large quantity of mass concentrated in the arm of the small sphere creates a significant moment

the bolts in the main chamber. A bar should be created between the small bars of the rack and the

nipple between the small sphere and (right) gate valve, on location B. The position of the bottom

support determines the position of this nipple and should therefore be placed exactly.

52

Part Product Code (Manufacturer) Mass (kg) Pcs

Large spherical cube MCF600-sphcube-F6C8 (Kimball Physics) 16.54 1

Small spherical cube MCF450-sphcube-E6A8 (Kimball Physics) 3.81 1

Ion pump 400L (Gamma Vacuum) 67.0 1

Small gate valve 300014 (MDC) 4.99 2

Diaphragm Pump MVP 015 (Pfeiffer Vacuum) 6.5 1

Turbo pump Hi Pace® 80 (Pfeiffer Vacuum) 3.8 1

Transfer arm 665100 (MDC) 4.54 1

FERP-HEAD (constructed at CTI, estimated weight) 2.0 1

Nipple 1 (turbo-molecular pump – small gate valve) 1.93 1

Nipple 2 (small gate valve – small sphere) 1.93 1

Nipple 3 (small sphere – small gate valve) 1.85 1

Nipple 4 (small gate valve – large sphere) 3.17 1

Nipple 5 (large sphere – large gate valve) 5.71 1

Crossing 9.18 1

TSP-Cryoshroud (Gamma Vacuum) 9.0 1

Residual Gas Analyzer (Stanford Research Systems) 2.1 1

Pirani gauge ConvecTorr (Agilent Technologies) * 0.3 1

Combination gauge FRG700 (Agilent Technologies) 0.98 1

Hot-cathode gauge Bayard Alpert UHV-24p (Agilent Technologies) * 1.0 1

Viewport large sphere MCF600-mtgflg-F1VP (Kimball Physics) 1.93 1

Viewport small sphere MCF450-mtgflg-E1VP (Kimball Physics) 0.80 1

CF16 blank flange CF16CG 0.04 8





Converter flange CF63 to CF40 CF63DF-40 1.09 2

Converter flange CF100 to CF63 CF100DF-63 2.11 1

Bolts and nuts (estimated weight) 2.0 1

Total mass 180.7 kg

Table 5.1 – all system parts and corresponding mass

The bottom bridge is created using two steel bars and a thick bottom plate. For the bars, a steel T-

section profile from the laboratory is used (the bottom bars of the rack are thin-walled square

profiles). A plate is used for the positioning of the ion pump. This plate does not have a structural

function and should therefore be thin and light. For all parts of the support, the exact steel type is

not known, because these are old parts from the laboratory.

*) only shipping weight available, thus estimated product weight


53

Figure 5.2 – a) available rack from DMI laboratory and b) CAD-model for placing FERP-system

Figure 5.3 shows the design of the support. Appendix D contains technical drawings that show the

design of the plate and its exact placement on the rack. The bottom plate is designed in that way,

that the bottom flange of the ion pump fits exactly in it. It is left to the opinion and experience of

the workshop how these bars and plate can best be fixed onto the rack. The support between the

rack and the nipple, which should be created top-right in Figure 5.3, is not further discussed in this

report. Furthermore, Vinicius L. Pimentel assures on experience that the complete steel support is

appropriate to carry the load imposed by the system. No structural calculations are carried out to

confirm this statement.

Figure 5.3 – design of bottom support with correct location for nipple 3 (top view)

54

Figure 5.4 shows the convenience of the use of the rack for the support structure. It can be closed

using thin metal plates for the bake-out procedure. The required temperature of 150 °C inside this

‘oven’ can be obtained using the heating system of the ion pump. As a reminder, Figure 3.14

showed the cover used for the bake-out of a STM. Because the system needs to be completely

closed, there must still be a structure designed that can be placed on top. This is not further

discussed here.

Figure 5.4 – rack can be closed for bake-out

It was mentioned that it is preferred that the support structure can be moved. To this end, four

small wheels from the laboratory are used to fix underneath the legs of the rack.

Once the support is completed, all heavy vacuum equipment can be placed in position using a

small crane. Then, the system can be cleaned, a bake procedure can be carried out, the system can

be pumped down to 5x10-12 Torr UHV and the FERP-experiment can be started. This concludes

the internship assignment.


55

6 Conclusion & recommendations

For this internship assignment two main goals were formulated: carry out a study into vacuum and

provide detailed designs of the required parts for the new FERP-system.

Of the first goal, the second and third chapter are the result. Vacuum principles and standard

equipment are neatly described, such that this document could be used as an introduction into

vacuum for those who are interested. It could be used to get to know the principles and

equipment of the new FERP-system. Therewith, the vacuum study is completed. For accurate

information about the FERP-method itself, the reader is advised to consult dedicated literature.

The designs discussed in chapter 4 are detailed up to the level of manufacturing. 7 designs are

provided here: 1 crossing, 5 nipples and 1 top-flange. These parts could be produced directly, as

soon as budget is available for manufacturing. Once these parts are completed, the FERP-system

can be built, which is already done on CAD-level in chapter 5. The CAD-model provides an accurate

indication for how the system needs to be constructed. It was also used to see whether an existing

support structure in the DMI laboratory was appropriate, which turned out to be the case. A

structural check may still be performed to assure that the rack is appropriate to carry the imposed

load.

At this time, detailed designs for all required parts of the new FERP-system are available. The

system can be completed as desired. The assignment is therefore satisfactory finalized. However,

for the FERP-system to function, a few more steps must be performed in the future. The top-cover

for bake-out must be provided and a redesign of the FERP-head is required for simultaneous

replacement of the sample plate and single atom tip cathode.

56

7 Reflection on the internship

This reflection does not only concern the project described in this report, but also all other

experiences I had regarding the internship. In the three months that this lasted, I had lots of new

experiences. But also before and after this period, it turned out to be an interesting challenge. I

was very welcome at CTI, where many University of Twente students had done their masters

internship in the past.

First, I had to go to the Brazilian consulate in Rotterdam and deliver them a load of documents to

obtain the Vitum IV visa. This process took about 2 months, but had the result that I could legally

stay as an intern in Brazil for 4 months. However, it turned out that in Brazil I had to go to the

Policia Federal, to legalize my visa. I knew this already, but what I did not know was that I had to

deliver more documents and payments. Another process that took about 3 weeks, which I could

not have done without the help of my colleagues at DMI. For example: all required information to

obtain the visa was only presented in Brazilian Portuguese. I learned my fair share of this language,

but was not able to translate the ‘deliverables to the Policia Federal’-list as accurate as needed.

Bureaucracy in Brazil turned out to be a challenge, which certainly affected the first weeks of my

assignment. However, I think that this is an important part of an international internship and I got

a whole new experience from it.

During the internship, I learned a lot about vacuum principles and equipment. This knowledge was

helpful, but not required to provide the designs. These turned out to be very straightforward.

Because design for vacuum systems is based on industry standards, my assignment turned out to

be ‘finding the right dimensions’ rather than doing a creative design process. To this end, I think

the part of vacuum study is closer to the academic level required in a master internship. This was

an interesting addition to the knowledge obtained in Mechanical Engineering.

The CAD-model provided some nice insights in the end of the internship, but I could have done

some structural calculations to increase the level of my report. To be true, I did, but in every

calculation the rack turned out to be critically loaded by the complete system. I did not include

these calculations in my report, because these were simplifications of reality and out of time

consideration not deeply checked. I communicated this to Vinicius L. Pimentel, but he was

‘absolutely sure’ that the rack will support the system, and so no further detail has to be spent to

this. If in my coming thesis such a question arises, I am dedicated to determine this correctly in

cooperation with my supervisor.

Besides the project described in this report, I did some smaller tasks to contribute the work of

DMI. In the first week I helped to manufacture a new sample plate for research at LNLS, by

providing technical drawings to the CTI workshop. Together with Vinicius, I repeatedly visited the

research facilities from LNLS. It was nice to see what types of research are carried out and what


57

specialized equipment is available here.

Another small project I did, was a redesign of the sample holder. Once the transfer arm arrived,

this sample holder turned out to have the wrong diameter fitting. A redesign was quickly made

and produced in the workshop, a matter of turning. The other designs formulated in this report

are unfortunately not manufactured there, due to budget constraints. This was also seen at the

end of my internship, when by coincidence a befriended facility of Belo Horizonte could lend a

DN150 T-crossing to CTI. The crossing design from this report was suddenly not needed anymore.

This is part of business and an additional experience to university projects, where your designs are

not simply replaced out of cost consideration.

To conclude the assignment, I did a presentation for the colleagues of DMI, partly in Portuguese

and English. In the end, the contents of this report may seem straightforward, but overall I think

that quantitatively I did a lot of things in the three months available. Regarding the university’s

goal of obtaining practical experience in the work field; it feels like I did this comprehensively. I

was in Brazil in the time of carnaval. I had a wonderful time, learned about the people’s customs,

the country and technically a lot about vacuum. This last part resulted in a complete report, that

was hopefully nice to read. I want to thank the people in Campinas for a great experience.

Top: visits to LNLS laboratory. Bottom: Crossing design from Belo Horizonte and presentation at DMI.

58

References

1. Anema J. Improvement of the Field Electric Retarding Potential Characterization System. Internship Report. Enschede: University of Twente, CTW; 2015. 2. CTI. Sobre o CTI 2014 [updated 27-07-2016; cited 2016 03-08-2016]. Available from: http://www.cti.gov.br/sobre-o-cti. 3. M. H. M. O. Hamanaka, F. F. Dall'Agnol, V. L. Pimentel, V. P. Mammana, P. J. Tatsch, D. den Engelsen. Work function measurements using a field emission retarding potential technique. 2016. 4. R. Strayer, W. Mackie, L. W. Swanson. Work function measurements by the field emission retarding potential method. Surface Science. 1973;34(2):225-48. 5. S. C. Barnes, K. E. Singer. FERP device for absolute work function measurements. Journal of Physics E: Scientific Instruments. 1977;10:737-40. 6. W. D. Farrow. Basic vacuum principles and measurement. Specialty Gas Report. 2009:38-41. 7. Pfeiffer Vacuum. Introduction to Vacuum Technology n.d. [28-03-2016]. Available from: https://www.pfeiffer-vacuum.com/en/know-how/introduction-to-vacuum-technology/general/. 8. Oxford Vacuum Science. Vacuum Regimes n.d. Available from: http://www.oxford-vacuum.com/background/high_vacuum/regimes.htm. 9. Thomas. Diaphragm n.d. [18-07-2016]. Available from: http://www.gd-thomas.com/technologies/diaphragm/. 10. W. Umrath. Fundamentals fo Vacuum Technology. In: Oerlikon Leybold Vacuum, editor. Cologne2007. 11. Pfeiffer Vacuum. Diaphragm vacuum pumps n.d. [cited 2016 17-07-2016]. Available from: https://www.pfeiffer-vacuum.com/en/know-how/vacuum-generation/diaphragm-vacuum-pumps/. 12. Pfeiffer Vacuum. Turbomolecular pumps n.d. [19-07-2016]. Available from: https://www.pfeiffer-vacuum.com/en/know-how/vacuum-generation/turbomolecular-pumps/. 13. Pfeiffer Vacuum. Classification of vacuum pumps n.d. Available from: https://www.pfeiffer-vacuum.com/en/know-how/vacuum-generation/vacuum-pumps-working-principles-and-properties/. 14. Gamma Vacuum. Ion Pump Operation n.d. [19-07-2016]. Available from: http://www.gammavacuum.com/index.php/theory-of-operation/. 15. Kurt J. Lesker Company. Pump Classifications Technical Notes n.d. [20-07-2016]. Available from: http://www.lesker.com/newweb/vacuum_pumps/vacuumpumps_technicalnotes_1.cfm. 16. Gamma Vacuum. Low Profile Ion Pumps 400L n.d. [19-07-2016]. Available from: http://www.gammavacuum.com/index.php/product?id=8. 17. Danielson P. How to match pumping speed to gas load 2000 [28-03-2016]. Available from: http://www.normandale.edu/departments/stem-and-education/vacuum-and-thin-film-technology/vacuum-lab/articles/how-to-match-pumping-speed-to-gas-load. 18. P. E. Barber. Penning Gauges - Theory of Operation 2000 [updated 25-07-200025-07-2016]. Available from: http://nucalf.physics.fsu.edu/~campbell/png_gag_theory.html. 19. Kurt J. Lesker Company. Pressure Measurement Technical Notes n.d. [04-08-2016]. Available from: http://www.lesker.com/newweb/gauges/gauges_technicalnotes_1.cfm. 20. Granville-Phillips. Introduction to Bayard-Alpert Ionization Gauges. 1999. 21. Pfeiffer Vacuum. Direct, gas-independent pressure measurement n.d. [25-07-2016]. Available from: https://www.pfeiffer-vacuum.com/en/know-how/vacuum-measuring-

http://www.cti.gov.br/sobre-o-cti

https://www.pfeiffer-vacuum.com/en/know-how/introduction-to-vacuum-technology/general/

http://www.oxford-vacuum.com/background/high_vacuum/regimes.htm

http://www.oxford-vacuum.com/background/high_vacuum/regimes.htm

http://www.gd-thomas.com/technologies/diaphragm/

http://www.gd-thomas.com/technologies/diaphragm/

https://www.pfeiffer-vacuum.com/en/know-how/vacuum-generation/diaphragm-vacuum-pumps/

https://www.pfeiffer-vacuum.com/en/know-how/vacuum-generation/diaphragm-vacuum-pumps/

https://www.pfeiffer-vacuum.com/en/know-how/vacuum-generation/turbomolecular-pumps/

https://www.pfeiffer-vacuum.com/en/know-how/vacuum-generation/vacuum-pumps-working-principles-and-properties/

https://www.pfeiffer-vacuum.com/en/know-how/vacuum-generation/vacuum-pumps-working-principles-and-properties/

http://www.gammavacuum.com/index.php/theory-of-operation/

http://www.lesker.com/newweb/vacuum_pumps/vacuumpumps_technicalnotes_1.cfm

http://www.gammavacuum.com/index.php/product?id=8

http://www.normandale.edu/departments/stem-and-education/vacuum-and-thin-film-technology/vacuum-lab/articles/how-to-match-pumping-speed-to-gas-load

http://www.normandale.edu/departments/stem-and-education/vacuum-and-thin-film-technology/vacuum-lab/articles/how-to-match-pumping-speed-to-gas-load

http://nucalf.physics.fsu.edu/~campbell/png_gag_theory.html

http://www.lesker.com/newweb/gauges/gauges_technicalnotes_1.cfm

https://www.pfeiffer-vacuum.com/en/know-how/vacuum-measuring-equipment/fundamentals-of-total-pressure-measurement/direct-gas-independent-pressure-measurement/


59

equipment/fundamentals-of-total-pressure-measurement/direct-gas-independent-pressure-measurement/. 22. Hositrad Vacuum Technology. Hositrad. www.hositrad.com. 23. Kurt J. Lesker Company. KF (QF) Flanges n.d. . Available from: http://www.lesker.com/newweb/flanges/flanges_technicalnotes_kf_1.cfm?pgid=0. 24. Kurt J. Lesker Company. CF Flanges Technical Notes n.d. [04-08-2016]. Available from: http://www.lesker.com/newweb/flanges/flanges_technicalnotes_conflat_1.cfm?pgid=0. 25. MDC Vacuum. Del Seal CF Flanges. http://www.mdcvacuum.com/DisplayContentPage.aspx?cc=f8c467bf-0008-4d34-9342-caaa07ee8d95. 26. M. B. da Silva. Componentes de Vácuo, Flanges Tipo CF. In: LNLS, editor. 1999. 27. MDC Vacuum. 665100 - Magnetic Transporter. n.d. 28. T. van Diepen. Design for Vacuum Systems. Internship report. Enschede: University of Twente, CTW; 2015. 29. M.G. Rao, C. Dong. Evaluation of low cost residual gas analyzers for ultrahigh vacuum applications. 1996. 30. Gamma Vacuum. Titanium Sublimation Pumping (TSP). In: Gamma Vacuum, editor. Shakopee, n.d. 31. Pfeiffer Vacuum. Bake-out n.d. [06-08-2016]. Available from: https://www.pfeiffer-vacuum.com/en/know-how/introduction-to-vacuum-technology/influences-in-real-vacuum-systems/bake-out/. 32. Kimball Physics. Close couplers n.d. [07-08-2016]. Available from: http://www.kimballphysics.com/multicf-hardware/products/specialty-fittings/close-couplers. 33. ASM Aerospace Specification Metals Inc. AISI Type 304 Stainless Steel. n.d. 34. Agilent Technologies. Agilent Vacuum Measurement. n.d. 35. Pfeiffer Vacuum. MVP 015. n.d.



http://www.hositrad.com/

http://www.lesker.com/newweb/flanges/flanges_technicalnotes_kf_1.cfm?pgid=0

http://www.lesker.com/newweb/flanges/flanges_technicalnotes_conflat_1.cfm?pgid=0

http://www.mdcvacuum.com/DisplayContentPage.aspx?cc=f8c467bf-0008-4d34-9342-caaa07ee8d95

http://www.mdcvacuum.com/DisplayContentPage.aspx?cc=f8c467bf-0008-4d34-9342-caaa07ee8d95

https://www.pfeiffer-vacuum.com/en/know-how/introduction-to-vacuum-technology/influences-in-real-vacuum-systems/bake-out/



http://www.kimballphysics.com/multicf-hardware/products/specialty-fittings/close-couplers

60

Datasheets references

Datasheets of the commercial components are not included in the appendix, but can be obtained

online using the following links:

Main chamber (Kimball): http://www.kimballphysics.com/mcf600-sphcube-f6c8

Small sphere (Kimball): http://www.kimballphysics.com/mcf450-sphcube-e6a8

Ion pump (Gamma): http://www.gammavacuum.com/index.php/product?id=8

Turbo-molecular pump (Pfeiffer): https://www.pfeiffer-

vacuum.com/en/products/turbopumps/hybrid-bearing/hipace-80/?detailPdoId=4511

Small gate valve (MDC):

http://www.mdcvacuum.com/DisplayProductContent.aspx?d=MDC&p=m.2.1.1.4

Transfer arm (MDC): http://www.mdcvacuum.com/DisplayPart.aspx?d=MDC&p=665100

Titanium Sublimation Pump (Gamma): http://www.gammavacuum.com/index.php/product?id=23

Liquid Cryoshroud (Gamma): http://www.gammavacuum.com/index.php/product?id=24

Viewport main chamber (Kimball): http://www.kimballphysics.com/mcf600-mtgflg-f1vp

Viewport small sphere (Kimball): http://www.kimballphysics.com/mcf450-mtgflg-e1vp

Hot-cathode gauge (Agilent): https://www.agilent.com/en-us/products/vacuum-

technologies/vacuum-measurement/transducers/uhv-24-bayard-alpert-gauge-tube

For information on the cold-cathode and Pirani gauge, datasheets from the Agilent catalog are

used (34). Information on the MVP 015 diaphragm pump is retrieved from its manual in the

database of CTI (35).

http://www.kimballphysics.com/mcf600-sphcube-f6c8

http://www.kimballphysics.com/mcf450-sphcube-e6a8


https://www.pfeiffer-vacuum.com/en/products/turbopumps/hybrid-bearing/hipace-80/?detailPdoId=4511

https://www.pfeiffer-vacuum.com/en/products/turbopumps/hybrid-bearing/hipace-80/?detailPdoId=4511

http://www.mdcvacuum.com/DisplayProductContent.aspx?d=MDC&p=m.2.1.1.4

http://www.mdcvacuum.com/DisplayPart.aspx?d=MDC&p=665100



http://www.kimballphysics.com/mcf600-mtgflg-f1vp

http://www.kimballphysics.com/mcf450-mtgflg-e1vp

https://www.agilent.com/en-us/products/vacuum-technologies/vacuum-measurement/transducers/uhv-24-bayard-alpert-gauge-tube

https://www.agilent.com/en-us/products/vacuum-technologies/vacuum-measurement/transducers/uhv-24-bayard-alpert-gauge-tube


61

Appendix A – Pump pressures

# Type Brand/Model Pumping

speed

Compressi

on Rate

N2

Ultimate

pressure

Rotation

speed

(rpm)

1 Mechanical/

Diaphagma

Pfeiffer Vacuum

MVP 008-4

4.8L/min

0.25m3/h NA

≤ 1.5 Torr

NA

2 Mechanical/

Diaphagma

Pfeiffer Vacuum

MVP 015-2

15L/min

0.70m3/h NA

≤ 2.62 Torr

NA

3 Turbomolecular Pfeiffer Vacuum

HiPace 10 10L/s 3.0E6 <3.75x10-5

Torr 90.000

4 Turbomolecular Pfeiffer Vacuum

HiPace 80 >67L/s >1.0E11

<3.75x10-10

Torr 90.000

5 Turbomolecular Leybold/TMP 361 400L/s >1.0E9

<7.5x10‐11

Torr 45.000

Pfeiffer MVP015-2

Pfeiffer Hipace 80 Curves

62

Appendix B – RGA spectrum

14

710

13

16

19

22

25

28

31

34

37

40

43

46

49

52

55

58

61

64

-10

1.0

x10

-91.0

x10

-81.0

x10

-71.0

x10

-61.0

x10

-51.0

x10

-41.0

x10

To

rrA

na

log

Sc

an

1.2

E-1

0

To

tal P

ressu

re

X =

18.1

Y =

4.7

5e-0

07

34:52:0744:49:52

54:47:3764:45:22

74:43:0784:40:52

94:38:37104:36:22

-8-2

.0x10

-71.0

x10

-72.3

x10

-73.5

x10

-74.8

x10

-76.0

x10

-77.3

x10

-78.5

x10

-79.7

x10

-61.1

x10

-61.2

x10

To

rrP

vs T

Sc

anT

ime:1

1:1

6:5

2

3.3

4e-0

08 N

itrog

en

1.6

0e-0

07 H

yd

rog

en

1.3

6e-0

06 W

ate

r

5.3

1e-0

09 O

xyg

en

1.0

3e-0

08 C

arb

on

dio

xid

e

3.6

7e-0

09 A

rgo

n

14

710

13

16

19

22

25

28

31

34

37

40

43

46

49

52

55

58

61

64

-10

1.0

x10

-91.0

x10

-81.0

x10

-71.0

x10

-61.0

x10

-51.0

x10

-41.0

x10

To

rrA

na

log

Sc

an

1.2

E-1

0

To

tal P

ressu

re

X =

18.1

Y =

4.7

5e-0

07


63

Appendix C – Standardized tube sizes

64

Appendix D – Technical drawings

152,10

148,10

152,10

148,10

292

292

BCD

12

A

32

14

B A

56

DRA

WN

CHK'D

APPV

'D

MFG

Q.A

UNLESS O

THERWISE SPEC

IFIED:

DIM

ENSIO

NS A

RE IN M

ILLIMETERS

SURFAC

E FINISH:

TOLERA

NC

ES: LIN

EAR:

AN

GULA

R:

FINISH:

DEBUR A

ND

BREA

K SHARP

EDG

ES

NA

ME

SIGN

ATURE

DA

TE

MA

TERIAL:

DO

NO

T SCA

LE DRA

WIN

GREVISIO

N

TITLE:

DW

G N

O.

SCA

LE:1:5SHEET 1 O

F 1

A4

C

WEIG

HT:

ggroenev28/01/2016

01/01

cryopannel_chamber

cyropannel chamber

152,10 148,10

152,10

148,10

CF150RR

CF150RR

CF150PD

CF150PD

316

203

316

203

BCD

12

A

32

14

B A

56

DRA

WN

CHK'D

APPV

'D

MFG

Q.A

UNLESS O

THERWISE SPEC

IFIED:

DIM

ENSIO

NS A

RE IN M

ILLIMETERS

SURFAC

E FINISH:

TOLERA

NC

ES: LIN

EAR:

AN

GULA

R:

FINISH:

DEBUR A

ND

BREA

K SHARP

EDG

ES

NA

ME

SIGN

ATURE

DA

TE

MA

TERIAL:

DO

NO

T SCA

LE DRA

WIN

GREVISIO

N

TITLE:

DW

G N

O.

SCA

LE:1:5SHEET 1 O

F 1

A4

C

Stainless Steel 304 or 316L

WEIG

HT:

ggroenev28/01/2016

cryo_assem

tube with flanges

BB

17,50 17,50 41

76

SECTIO

N B-B

SCA

LE 1 : 2

CF63RR

Tube_Nipple1

CF63PD

BCD

12

A

32

14

B A

56

DRA

WN

CHK'D

APPV

'D

MFG

Q.A

UNLESS O

THERWISE SPEC

IFIED:

DIM

ENSIO

NS A

RE IN M

ILLIMETERS

SURFAC

E FINISH:

TOLERA

NC

ES: LIN

EAR:

AN

GULA

R:

FINISH:

DEBUR A

ND

BREA

K SHARP

EDG

ES

NA

ME

SIGN

ATURE

DA

TE

MA

TERIAL:

DO

NO

T SCA

LE DRA

WIN

GREVISIO

N

TITLE:

DW

G N

O.

SCA

LE:1:5SHEET 1 O

F 1

A4

C

WEIG

HT:

Nipple1

56

64

60

BCD

12

A

32

14

B A

56

DRA

WN

CHK'D

APPV

'D

MFG

Q.A

UNLESS O

THERWISE SPEC

IFIED:

DIM

ENSIO

NS A

RE IN M

ILLIMETERS

SURFAC

E FINISH:

TOLERA

NC

ES: LIN

EAR:

AN

GULA

R:

FINISH:

DEBUR A

ND

BREA

K SHARP

EDG

ES

NA

ME

SIGN

ATURE

DA

TE

MA

TERIAL:

DO

NO

T SCA

LE DRA

WIN

GREVISIO

N

TITLE:

DW

G N

O.

SCA

LE:1:2SHEET 1 O

F 1

A4

C

WEIG

HT:

Tube_Nipple1

AA

17,50

20

37,50

75

SECTIO

N A

-ASC

ALE 1 : 2

CF63RR

Tube_Nipple2

CF100TD

_63

BCD

12

A

32

14

B A

56

DRA

WN

CHK'D

APPV

'D

MFG

Q.A

UNLESS O

THERWISE SPEC

IFIED:

DIM

ENSIO

NS A

RE IN M

ILLIMETERS

SURFAC

E FINISH:

TOLERA

NC

ES: LIN

EAR:

AN

GULA

R:

FINISH:

DEBUR A

ND

BREA

K SHARP

EDG

ES

NA

ME

SIGN

ATURE

DA

TE

MA

TERIAL:

DO

NO

T SCA

LE DRA

WIN

GREVISIO

N

TITLE:

DW

G N

O.

SCA

LE:1:5SHEET 1 O

F 1

A4

C

WEIG

HT:

Nipple2

54 64

60

BCD

12

A

32

14

B A

56

DRA

WN

CHK'D

APPV

'D

MFG

Q.A

UNLESS O

THERWISE SPEC

IFIED:

DIM

ENSIO

NS A

RE IN M

ILLIMETERS

SURFAC

E FINISH:

TOLERA

NC

ES: LIN

EAR:

AN

GULA

R:

FINISH:

DEBUR A

ND

BREA

K SHARP

EDG

ES

NA

ME

SIGN

ATURE

DA

TE

MA

TERIAL:

DO

NO

T SCA

LE DRA

WIN

GREVISIO

N

TITLE:

DW

G N

O.

SCA

LE:1:2SHEET 1 O

F 1

A4

C

WEIG

HT:

Tube_Nipple2

AA

20

22

42

84

SECTIO

N A

-ASC

ALE 1 : 3

CF100RR

Tube_Nipple3

CF150TD

_100

BCD

12

A

32

14

B A

56

DRA

WN

CHK'D

APPV

'D

MFG

Q.A

UNLESS O

THERWISE SPEC

IFIED:

DIM

ENSIO

NS A

RE IN M

ILLIMETERS

SURFAC

E FINISH:

TOLERA

NC

ES: LIN

EAR:

AN

GULA

R:

FINISH:

DEBUR A

ND

BREA

K SHARP

EDG

ES

NA

ME

SIGN

ATURE

DA

TE

MA

TERIAL:

DO

NO

T SCA

LE DRA

WIN

GREVISIO

N

TITLE:

DW

G N

O.

SCA

LE:1:5SHEET 1 O

F 1

A4

C

WEIG

HT:

Nipple3

60,50

97,60

101,60

BCD

12

A

32

14

B A

56

DRA

WN

CHK'D

APPV

'D

MFG

Q.A

UNLESS O

THERWISE SPEC

IFIED:

DIM

ENSIO

NS A

RE IN M

ILLIMETERS

SURFAC

E FINISH:

TOLERA

NC

ES: LIN

EAR:

AN

GULA

R:

FINISH:

DEBUR A

ND

BREA

K SHARP

EDG

ES

NA

ME

SIGN

ATURE

DA

TE

MA

TERIAL:

DO

NO

T SCA

LE DRA

WIN

GREVISIO

N

TITLE:

DW

G N

O.

SCA

LE:1:2SHEET 1 O

F 1

A4

C

WEIG

HT:

Tube_Nipple3

AA

Use design of CF100DF ´dupla face´towards CF63 tube, but applyadjusted inner diameter of 64 mm.

64

77,20 82,60

152

20

SECTION A-ASCALE 1 : 2

Top viewC

2 31 4

B

A

D

E

F

CF100_DFWEIGHT:

A4

SHEET 1 OF 1SCALE:1:5

DWG NO.

TITLE:

REVISIONDO NOT SCALE DRAWING

MATERIAL:

DATESIGNATURENAME

DEBUR AND BREAK SHARP EDGES

FINISH:UNLESS OTHERWISE SPECIFIED:DIMENSIONS ARE IN MILLIMETERSSURFACE FINISH:TOLERANCES: LINEAR: ANGULAR:

Q.A

MFG

APPV'D

CHK'D

DRAWN

1. Plain Rack

2. Rack with support beams

3. Rack with bottom plate

4. With vacuum system placed

5. Detail support

90

624

300

90

243

300

5

BCD

12

A

32

14

B A

56

DRA

WN

CHK'D

APPV

'D

MFG

Q.A

UNLESS O

THERWISE SPEC

IFIED:

DIM

ENSIO

NS A

RE IN M

ILLIMETERS

SURFAC

E FINISH:

TOLERA

NC

ES: LIN

EAR:

AN

GULA

R:

FINISH:

DEBUR A

ND

BREA

K SHARP

EDG

ES

NA

ME

SIGN

ATURE

DA

TE

MA

TERIAL:

DO

NO

T SCA

LE DRA

WIN

GREVISIO

N

TITLE:

DW

G N

O.

SCA

LE:1:20SHEET 1 O

F 1

A4

C

WEIG

HT:

plate_location

Date post:	07-May-2018
Category:	Documents
Upload:	nguyenkhanh
View:	215 times
Download:	1 times

Design of vacuum components for FERP-techniqueessay.utwente.nl/71925/1/Internship_report_CTI -...

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