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Allan DeMello Lawrence Berkeley National Lab RFCC Module Design Review October 21, 2008 RFCC Module and Subcomponents Mechanical Design
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Allan DeMelloLawrence Berkeley National Lab
RFCC Module Design Review
October 21, 2008
RFCC Module and Subcomponents Mechanical Design
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
Page 2Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 2Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
RFCC Module Components
Dynamic Cavity Frequency Tuners
Hexapod StrutCavity Suspension
RF Cavity Water Cooling
Mechanical Joiningof the Coupling Coiland the Vacuum Vessel
Vacuum System
RF Coupler
RFCCSupport Stand
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 3Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 3Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Four Cavity Layout in Vacuum Vessel
•Clocking of tuner position between adjacent cavities avoids interference
•Actuators offset from cavity center plane due to width of coupling coil
•No contact between pairs of close packed cavities
•Tuning deflections increase cavity gap
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 4Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 4Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Module End View with Tuners
•Six tuners per cavity provide individual frequency adjustment
•Tuning automatically achieved through a feedback loop
•24 tuners required for each RFCC module
•Soft connection only (bellows) between tuner/actuators and vacuum vessel shell
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 5Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 5Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Cavity Tuner Design Features
•Tuners are spaced evenly every 60º around cavity
•Layout is offset by 15º from vertical to avoid conflict with cavity ports
•Tuners touch cavity and apply loads only at the stiffener rings
•Tuners operate in “push” mode only (i.e. squeezing)
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 6Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 6Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Cavity Tuner Components - Section View
Ball contact only
Dual bellowsvacuum sealing
Tuner actuator Pivot pin
Fixed (bolted)connection
Ceramic contact wear plate between actuator ball end and tuner arm
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 7Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 7Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Tuner Component Details
Fixed arm
Pivoting arm
Actuator with integrated bellowsassembly
Screws to attach tuner to the cavity stiffener ring
Pivot pinCylinder attachment bracket
Forces are transmitted to the stiffener ring by means of “push” loads applied to the tuner lever arms by the actuator assembly
Ceramic wear plate
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 8Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
Actuator Design
RFCC Module and Subcomponents Mechanical Design
Page 8Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
•Actuator design incorporates bellows sealing between vacuum and air (no rubber).
•Actuator is “soft” mounted to the vacuum vessel with a bellows
Ceramic plate attached to the tuner arm
Hemisphere attached to the end of actuator rod
Page 9
• Senior Aerospace Bellows will be fabricating the actuators (near off the shelf)
Actuator Supplier
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Stiffener Ring Analysis - Applied Displacement
Page 10
• A displacement of 2 mm is applied to both sides of the cavity stiffener ring in 6 locations
• Maximum observed distortion of 0.05 mm (0.002”) in the stiffener ring
• This level of distortion is not expected to affect the RF performance of the cavity or the overall stress on the Be window
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 11
• A reaction force of 31811 N (per side) on the stiffener ring is calculated in ANSYS
• 31811 N (per side) must be supplied by the 6 tuners
• Each tuner must apply 5300 N per side
•
Tuner System Analysis – Reaction Force
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
Page 12Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 12Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Tuner System Analysis - Deformation
• ANSYS FEA of one tuner on 1/6 cavity segment
• Input pressure of 1.38 MPa (200 psi) is applied to actuator piston
•Deformation at the stiffener ring in the 2 mm range
•Movement of the arm at the actuator is in the 3 mm range
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
Page 13Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 13Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Tuner System Analysis - Stress
• ANSYS FEA of one tuner on 1/6 cavity segment
• Maximum stress in the cavity in the 100 MPa (14500 psi) range• The yield strength of
the copper cavity is 275 MPa• This analysis show that the cavity will not yield when compressed by the tuner arms
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 14Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 14Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Cavity Tuning Parameters
The following parameters are based on a finite element analysis of the cavity shell. Tuning range is limited by material yield stress.
•Overall cavity stiffness: 7950 N/mm
•Tuning sensitivity: +230 kHz/mm per side
•Tuning range: 0 to -460 kHz (0 to -2 mm per side)
•Number of tuners: 6
•Maximum ring load/tuner: 5.3 kN
•Max actuator press. (100 mm): 1.38 MPa (200 psi)
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 15Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 15Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Cavity Suspension System
•Each cavity contains a dedicated set of suspension struts
•The suspension struts are designed to axially fix the cavity inside the vacuum vessel
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 16Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 16Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Hexapod Strut Arrangement
•Hexapod six strut system will provide kinematic cavity support
•Each cavity requires a dedicated set of 6 suspension struts arranged in a hexapod type formation
•This system spreads the gravity load of the cavity across several struts
•Hexapod layout of struts allows accurate cavity alignment and positioning
•Six strut kinematic mounts prevent high cavity stresses caused by thermal distortion and over-constraint
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 17Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
Hexapod Strut Cavity Mounting
RFCC Module and Subcomponents Mechanical Design
Page 17Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
•Copper mounting post will be e-beam welded directly to the RF cavity
•The cavity experiences very little deformation on the radius at mounting post location during tuner deflection
•Stainless steel mounting post welded directly to the vacuum vessel
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 18Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
Hexapod Strut Mounting to Vessel
RFCC Module and Subcomponents Mechanical Design
Page 18Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Stainless steel strut mounts welded to the inside of the vacuum vessel
Copper strut mounts e-beam welded to the outside of the cavity
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 19Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 19Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
ANSYS FE Analysis - Deformation
•ANSYS FE analysis of the hexapod strut cavity suspension system
•Total mass of the cavity and tuners is approximately 410 kg. (900-lbs)
•Total deflection due to gravity alone is 0.115 mm
ANSYS FE Analysis - Stress
Page 20
•Maximum stress in the strut suspended cavity, due to gravity alone, is in the 20-30 MPa (2900-4350 psi) range
•Yield strength of cavity is in the 275 MPa range
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
ANSYS FE Analysis - Stress
Page 21
•Maximum stress due to gravity in the strut suspended cavity is in the 20-30 MPa (4500 psi) range
•Yield strength of cavity is in the 275 MPa range
•No yielding will take place in the cavity at the strut mounting locations
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 22
• ANSYS FE analysis showing first mode natural frequency result of 43 Hz
ANSYS FEA – Modal Analysis
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
• Support systems with a first mode frequency of 20 Hz or higher are generally considered a stiff structure
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October Allan DeMello - Lawrence Berkeley National Lab - October 20, 200820, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 13Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 23Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Cavity Cooling System
•Single circuit water cooling tube for each cavity
•One inlet and one outlet
•8 penetrations in the vacuum vessel
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October Allan DeMello - Lawrence Berkeley National Lab - October 20, 200820, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 13Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 24Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Cavity Cooling Water Feedthroughs
•All cavity water connections are made outside of the vacuum vessel
•Continuous water tube wrapped around the cavity
•A compliance coil inside of the vacuum vessel
•One inlet and one outlet per cavity
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October Allan DeMello - Lawrence Berkeley National Lab - October 20, 200820, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 13Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
RFCC Module and Subcomponents Mechanical Design
Page 25Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Section View of Water Feedthroughs
•A special conflat flange is welded into the wall of the vacuum vessel
•Both ends of the continuous copper tube are soft solder brazed (individually) into a second special conflat flange
• The second flange is fastened from the outside of the vacuum vessel
Vacuum side
Air side
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 26Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
Prototype Cavity RF Couplers
RFCC Module and Subcomponents Mechanical Design
Page 26Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
•Coupling loops are fabricated using standard copper co-ax
•Parts to be joined by e-beam welding (where possible) and torch brazing
•Coupling loop has integrated cooling
•The RF coupler will be based on the SNS design using the off the shelf Toshiba RF window
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 27Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
MICE Cavity RF Couplers
RFCC Module and Subcomponents Mechanical Design
Page 27Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
•A bellows connection between the coupler and the vacuum vessel provides compliance for mating with the cavity
•A simple copper flange is used to electrically connect the RF coupler to the cavity
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 28Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
MICE Cavity RF Couplers
RFCC Module and Subcomponents Mechanical Design
Page 28Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Off the shelf stainless steel flange “V” clamp secures RF coupler to cavity
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 20, 2008
MICE RF Cavity – Mechanical Design and Analysis
Page 29Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008
Vacuum System
RFCC Module and Subcomponents Mechanical Design
Page 29Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
•A NEG pump has been chosen because it will be unaffected by the large magnetic field
•A vacuum path between the inside and outside of the cavity eliminates the risk of high pressure differentials and the possible rupture of the thin beryllium window
NEG (non-evaporable getter) pump
Cross sectional view of vacuum system
Page 30
Vacuum Vessel Fabrication
Page 30
•Vacuum vessel material must be non-magnetic and strong: therefore 304 stainless steel will be used throughout
•The vacuum vessel will be fabricated by rolling stainless steel sheets into cylinders
•Two identical vessel halves will be fabricated with all ports and feedthroughs
Main 1400mm rolled tube
Smaller diameter rolled tube
Bellowsflange
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 31
The Two Halves Joined(coupling coil not shown)
Page 31
• Central under-cut provides clearance for the coupling coil
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 32
Cross Sectional View with the Coupling Coil
Page 32
Gap between the vacuum vessel and the coupling coil provides clearance for assembly
Vessel welded around the inside after coupling coil and the second vessel half are in place
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 13Page 33
Interface of Coupling Coil to the Vacuum Vessel
•Two 25 mm thick special gussets are welded to the coupling coil at ICST in Harbin
•These gussets are designed to match LBNL’s large load carrying gussets
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 13Page 34
Interface of Coupling Coil to the Vacuum Vessel
•LBNL will weld 25 mm thick special gussets between the coupling coil and the vacuum vessel
•These gussets are designed to match the gussets welded to the coupling coil at ICST
•No welding will be applied to the coupling coil external surfaces
•Opening in gusset provides access to the tuner actuator
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 13Page 35
Interface of Coupling Coil to the Vacuum Vessel
•Sixteen gussets will be used (8 on each side) to secure the coupling coil to the vacuum vessel
•Analysis still needs to be performed to confirm this design
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 36
RFCC Module Support Stand
Page 36
• Because the plan is to ship the RFCC module from Berkeley to RAL horizontally a special support stand will be fabricated that supports the coupling coil/vacuum vessel horizontally (without cavities installed)
• The RFCC will be moved into the experiment hall in the horizontal position on the shipping stand
• The permanent stand will be fabricated out of non-magnetic stainless steel
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
The Permanent RFCC Stand
Page 37
RFCC Attachment to Support Stand
Page 37
• The permanent support stand is bolted onto the vacuum vessel once the module is inside the experiment hall
• The vacuum vessel is bolted to a saddle made up of stainless steel plates welded to the support stand
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
• Stainless steel bars are welded onto the vacuum vessel for attaching bolted gusset plates
Page 38
RFCC Support Stand
Page 38
• RFCC support stand must withstand a longitudinal force of 50 tons transferred from the coupling coil
• Bolted stainless steel gusset plates and rectangular tube cross bracing provide shear strength in the axial direction (analysis will be done to confirm this stand design)
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 39
RFCC Module Design Summary
Page 39
• Conceptual design of the cavity frequency tuners is complete (further detailed analysis will be performed to optimize design)
• The hexapod cavity suspension system has been analyzed and will provide accurate alignment and rigid support for the cavities
• Cavity water cooling feed through system has been developed – minimum vacuum vessel penetrations needed
• The RF coupler will be based on the SNS design using the off the shelf Toshiba RF window
• The vacuum system includes an annular feature coupling the inside and the outside of the cavity (further analysis of vacuum needs to be done)
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
Page 40Page 40
• Engineering 3D CAD model of the vacuum vessel mechanical design is nearing completion
• Standard machining and manufacturing method will be used in the vacuum vessel’s fabrication
• Meyer Tool & Manufacturing has shown an interest in fabricating the vacuum vessel for us
• A plan for attaching the coupling coil and the vacuum vessel together has been developed and communicated to ICST for deployment
• Conceptual design of the support stand is complete (analysis will need to be performed)
RFCC Module Design Summary
RFCC Module and Subcomponents Mechanical Design
Allan DeMello - Lawrence Berkeley National Lab - October 21, 2008
