INT SRF19 CGDINA5 20s - SRF2019 · Peter Michel, HZDR, IPC Chair Claire Antoine, CEA Saclay Olivier...

SRF 19DRESDEN

www.srf2019.org

CONFERENCE CHAIR: Peter Michel (HZDR)

LOCAL ORGANIZING COMMITTEE CHAIR: André Arnold (HZDR)

CONFERENCE CHAIR: Peter Michel (HZDR)

LOCAL ORGANIZING COMMITTEE CHAIR: André Arnold (HZDR)

Foto: Frederik Schrader DML BY

hosted by

CONFERENCE GUIDE

th thJune 30 – July 5 , 2019 | Hotel Hilton Dresden

SRF 2019

19th International Conference on RF Superconductivity

June 30th – July 5th, 2019Hilton Hotel, Dresden, Germany

www.srf2019.org

Organized and Hosted byHelmholtz-Zentrum Dresden-Rossendorf (HZDR)

Supported byGSI Helmholtzzentrum für Schwerionenforschung

Helmholtz-Zentrum Berlin (HZB)Deutsches Elektronensynchtrotron (DESY)

ii SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

WELCOME

Dear Colleagues,

It is my pleasure, on behalf of the SRF2019 organizing committees, to welcome you to the19th International Conference on RF Superconductivity (SRF2019) at the Hilton Hotel in Dresden. Overlooking the Elbe River and the famous Frauenkirche, the venue is ideally located in the heart of the historic city, allowing easy access to all major monuments. The Conference will be hosted by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR).

Impressive advances in superconducting RF science and technology over the last four decades are responsible for a dramatic increase of SRF installations world-wide. RF superconductivity is currently the key technology of many accelerators for particle physics, nuclear physics and light sources. Free-Electron Lasers, such as the European XFEL with its 1.7 km long super-conducting LINAC or the upcoming European Spallation Source are just two exciting examples of the varied applications of SRF.

Continuing the successful tradition of 18 previous conferences, SRF 2019 will provide a stimulating forum for scientists, engineers, students and industrial partners to present and discuss the latest developments in SRF science and technology. The program will consist of invited talks, poster sessions and a 'hot-topic' discussion, as well as a boat trip into the Saxon Switzerland with its beautiful Sandstone Mountains. As in previous conferences, special tutorial sessions were held prior to the conference from June 27-29 at the campus of HZDR. These sessions are designed to provide an in-depth overview of SRF related subjects for scientists and engineers new to the field, or those who simply want a refresher. In this context, we are proud that with your participation and the generous contributions of the industrial exhibitors and sponsors, we have been able to support a significant number of young researchers from all three regions.

We look forward to your contribution to make this event an occasion for an exciting and fruitful exchange of ideas between industry and research institutes, across countries and domains, among younger and more experienced colleagues enjoying the superb setting of the “Florence of the North”.

Sincerely,

Peter MichelConference Chairman, SRF 2019

SRF 19 — Dresden, Germany — June 30th – July 5th, 2019 iii

INTERNATIONAL PROGRAM COMMITTEE

Peter Michel, HZDR, IPC ChairClaire Antoine, CEA SaclayOlivier Brunner, CERNJean Delayen, ODU (JACoW Liaison)Anna Grassellino, FNALEiji Kako, KEKMichael Kelly, ANLJens Knobloch, HZBMatthias Liepe, Cornell Kexin Liu, PKUCharles Reece, JLABDetlef Reschke, DESYKenji Saito, FRIBTsuyoshi Tajima, LANL

Special Regional Advisors: Robert Laxdal, TRIUMFAlberto Facco, INFNDong-O Jeon, IBS

LOCAL ORGANIZING COMMITTEE

Peter Michel, Conference ChairPetra Neumann, Conference Coordination & EditorAndré Arnold, Local Chair

Michael J. Klopf, ConsultingUlf Lehnert, ELBE TourSiegmar Lieber, Computing ServicesSylvia Neumann (INTERCOM Dresden GmbH), Conference OrganizationVolker RW Schaa, SPMSJana Schaber, Poster CoordinationChristof Schneider, Exhibition/SponsoringRong Xiang, Tutorial Klaus Zenker, Student Program

JACoW TEAM OF EDITORS

Robert Apsimon, CILUDong-Eon Kim, PALMaxim Kuzin, NSKMichaela Marx, DESYAnastasia Lesage, MSU MichiganPetra Neumann, HZDRChristine Petit-Jean-Genaz, CERNVolker RW Schaa, GSIJana Thomson, TRIUMF

iv SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

CONFERENCE VENUEthThe 19 International Conference on RF Superconductivity (SRF2019) will take

place from June 30 to July 5, 2019 at the Hilton Dresden Hotel.

Hilton Dresden

An der Frauenkirche 501067 Dresden

phone: +49 (0)351 8642-0web: www.hiltonhotels.de/deutschland/hilton-dresden

SRF 19 — Dresden, Germany — June 30th – July 5th, 2019 v

INTERNET ACCESS

Wireless internet access is available.

PUBLIC TRANSPORT

Dresden offers a very good transport infrastructure of train, tram and bus.

REGISTRATION

There are three categories of registration: Regular, Student / Postdoc and Extra Exhibitor.

· A regular participant is an individual from university, research lab orindustry wanting to participate in the full program.

· The student / participant is a student (PhD, master, or bachelor) enrolledin a university program OR a postdoc within 2 years after receiving theirPhD degree. To be eligible for this category the student must provide a copyof a document certifying your enrollment in the academic institution or youremployment as a post-doc and the year of your PhD.

· The extra exhibitor category is for companies that have already purchaseda booth but want to send supplementary industrial representatives to assistthe Exhibitor.

Registration Hours

On-site registration will take place from 16:00 to 20:00 on Sunday, 30 June at the conference venue.T hereafter the registration desk will be open as follows:

Monday July 01, 2019 07:30 – 18:00Tuesday July 02, 2019 08:00 – 18:00Wednesday July 03, 2019 08:00 – 13:30Thursday July 04, 2019 08:00 – 18:00Friday July 05, 2019 08:00 – 13:00

The registration fee for regular late registration is 650 Euros, for students 390 Euros. Payment at the registration desk must be in cash or by credit card.

The registration fee includes all congress materials, participation in sessions, the welcome reception, the excursion and conference dinner and coffee breaks.

Participants and accompanying persons are required to wear the official conference name badge on all conference occasions.

vi SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

TOURIST INFORMATION

You would like to see the main hotspots of Dresden? Below are some informa-tion that may be useful for planning your tourism activities. The best way to see the most highlights of Dresden in short time is by bus. Book a great city tour with “hop off, hop on” at 22 stops.

Old Town

On the left bank of the Elbe is Dresden's historical centre with buildings from the Renaissance, the Baroque and the 19th century. Despite being devastated in the Second World War, the Altstadt (Old Town) has kept or regained its attractive buildings.

The most well-known symbol of the rebuilding of the city centre is Dresden Frauenkirche (Church of Our Lady), the magnificent domed Baroque church which again dominates the Dresden skyline. After the Second World War, Neumarkt square and the symbolic ruins of the Frauenkirche remained almost untouched for half a century before also coming up for construction.

Museums, Art and Culture

50 museums, 60 galleries and 36 theatres and stages – a true pleasure for the emotions and intellect alike, and ideal day and evening programmes for every taste and mood.

World-famous attractions are the Old Masters Picture Gallery with Raphael’s “Sistine Madonna”, the former royal treasure collection, the Green Vault and the Albertinum as a museum of contemporary art from the 19th to 21st centuries.

Dresden has earned a similar world reputation as a city of music, with traditions stretching back over 700 years. The Semper Opera House, the Staatskapelle orchestra, the Dresden Philharmonic and the Kreuzchor choir are ample testimony.

Attractive festivals, exciting theatre and dance productions, and a series of top events are occasions for a visit to the city whatever the season.

Dresden – a top shopping destination

Shopping in Dresden is characterized by just as much exciting variety as the city itself. The city’s broad, for the most part pedestrianized high street begins right opposite the main station and continues along Prager Straße and over the Altmarkt and the Altmarkt-Galerie to Wilsdruffer Straße.

The historic quarter that nestles around the Frauenkirche is also just a short stroll away and boasts a whole host of shops and boutiques offering a wonder-ful selection of outstanding products.

The Baroque Quarter on the opposite side of the river is renowned for its many luxury outlets and culinary highlights – and just as its ends the "Äußere Neustadt" with its trendy shops, bars and cafés begins.

Further information about Dresden can be find under www.dresden.de.

SRF 19 — Dresden, Germany — June 30th – July 5th, 2019 vii

arnoldaDurchstreichen

arnoldaEingefügter Textinformation

Currency

The German currency is EURO (€). The official exchange rate is published daily in the newspapers. Exchange facilities are available at the airport, main train stations and exchange agencies. Cash and travelers checks are easily exchanged in banks and hotels. Most hotels and restaurants accept international credit cards. Exchange rates may vary. To see current exchange rates, please visit www1.oanda.com/currency/converter/

Credit Cards

Credit cards are accepted at most businesses including restaurants, shopping centers (malls) and gift stores, gas stations, grocery stores. Major credit cards include Visa, MasterCard, and American Express. ATMs are also located at many areas throughout Dresden.

Tipping

Tipping in restaurants and bars is generally at 5-10%.Tipping taxi drivers is also a common practice.

Climate and Temperatures in Dresden

Dress code during the conference is business casual and casual on the excursion days.June/July it is summer in Dresden/Germany and the average temperature is 22°C (72 °F). Please note there may be occasional showers. Weather information and forecasts are available at www.wetter.comWeather information and forecasts are available:http://www.wetter.com/deutschland/dresden/DE0002265.htmlWalking shoes are recommended for casual wear and excursions.

Electricity

Electric sockets are 230 volts AC, 50 Hz European-style round two-pin plugs are in use. You need a transformer and a plug that fits the German socket.

Disclaimer

The organizers are not liable for damages and/or losses of any kind which may be incurred by the congress delegates or by any other individuals accompanying them, both during the official activities as well as going to/from the congress. Delegates are responsible for their own safety and belongings.

Insurance

The SRF 2019 organizers do not accept liability for individual medical, travel or personal insurance, and participants are strongly advised to contract their own personal insurance.

Time Differences

Dresden, Germany is in Central European SummerTime in June.

viii SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

SOCIAL PROGRAMME

Welcome ReceptionSunday, 30 June,18:00 – 20:00

The welcome-reception will take place at the Hilton Dresden Hotel (venue).

Excursion and Conference Dinner Wednesday, 03 July, 16:00 – 23:00

The two hours excursion is in advance of the conference dinner. A guided walking tour through the historical city center of Dresden will give you the chance to see the most famous buildings of the city, e.g. the Royal Palace or the Church of our Lady. The tour will end at the “Brühlsche Terrasse” the balcony of Europe where the boat trip starts for the Dinner. Enjoy the unique boat trip to Pillnitz. Here you will have a guided visit to the famous park of the castle. You can enjoy your dessert while the boat returns to Dresden.

Reservations at the online registration are necessary. We recommend comfortable footwear.

Meeting-Point: Lobby of the Hilton Dresden HotelTime: 15:45

STUDENTS GRANTS

Financial Support for tudents

Limited financial support in order to promote student participation was made available. For supported students all fees are waived and free accommo-dation was organized. Depending on available funds accommodation was partially offered as double rooms shared by two students.

To be eligible for the student program the individual must:

· Be a student (PhD, master, or bachelor) enrolled in a university program ora postdoc within 2 years after receiving their PhD degree.

· Be working in the field related to the topics covered by the SRFconference.

· Submit an abstract to the conference.· Be able to attend the entire conference and tutorial.· Be willing to assist the LOC during the conference.

S

SRF 19 — Dresden, Germany — June 30th – July 5th, 2019 ix

Student support was allocated based on the following criteria:

· The relevance of the student's research to the field.· Whether the student is the primary author of a contribution to theconference.

· The reference letter from a supervisor.· The available funds.All supported students are expected to present a poster in the students postersession. In accordance with the guidelines for publication of contributions, these posters must also be displayed during the regular poster sessions. In addition, all supported students will be assigned light duties during the conference, such as assisting the session chair, passing microphones during question periods, preparing the poster sessions and working with the conference secretariat.

YOUNG INVESTIGATOR PRIZES

The conference honors the two best young scientists. The best talk of theconference as well as the best poster during the Student Poster Session onSunday will be selected by the International Program Committee and honored during the closing ceremony on Friday. The prize money is expected to be € 1000 for the talk and € 500 for the best poster. Decisive for the nomination is that the graduation to PhD is no longer than 3 years ago. The IPC selects the winners on the basis of the following criteria:

1. Relevance and impact of the scientific work,2. Novelty and quality of the scientific work,3. Quality of the poster and oral presentation,4. Interaction and professionalism towards the IPC.

SCIENTIFIC PROGRAMME

Programme Codes

All contributions to the scientific program have a code whereby:

• generally, the first two letters correspond to the day of presentation,Monday, Tuesday, Wednesday, etc. (i.e., MO, TU, WE etc.),

• for orals the next two letters indicate the classification (FA = facility, FU =fundamentals, TE = technology, CA = cavities, KN = keynote, and HT =hot topic), the fifth letter stands for morning session A or B and the lastdigit corresponds to the talk number in each session,

• for poster presentations the third letter is simply P for poster and theprogram code finishes with three digits corresponding to the poster panelnumber,

• the Sunday Student Poster session is named SUSP followed by a number.As these posters are shown again during the poster sessions on Monday,Tuesday or Thursday they have a second (main) code which is used foruploading the contribution.

x SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

Oral presentation

Oral sessions will be held in the main conference hall from Monday to Friday 8:00 to 13:00. A preview/testing room is available for speakers in the Salon Berlin within the Business Center. Please note that all speakers must give their presentations using the computer system that is in the main conference hall. We will provide both a Windows (with Microsoft Office) and a MacOS based system. Use of individual laptops cannot be accommodated. All talks MUST be uploaded at least 24 hours in advance using your SPMS account.

Poster Sessions

The poster boards will have a single surface measuring 2.5 m x 1 m (8,2 ft x 3,28 ft). They will accommodate an A0 or ARCH sized poster. The sessions will take place on Monday, Tuesday and Thursday between 14:30 and 18:00 in the Rossini Hall. The poster sessions include a 30-minute coffee break.

Posters should be placed before the beginning of the scheduled session time, manned during the session and taken down at the end of the session. Any posters not removed by 21:00 each day will be removed by staff and discarded.

Authors are reminded that no contributions are accepted for publication only. The Scientific Program Committee reserves the right to refuse

papers for publication that have not been properly presented or staffed in the poster sessions. Manuscripts of contributions to the proceedings (or enlargements of them) are not considered to be posters, and papers presented in this way will not be accepted for publication.

The suggested usage is the display of an A0/ARCH E page in Portrait orientation on the boards.

Note: You have to avoid LANDSCAPE orientation for A0 and ARCH E formats, since it will be too wide to fit in the poster boards!

SRF 19 — Dresden, Germany — June 30th – July 5th, 2019 xi

Student Poster Session

The SRF conference series are characterized by focusing on the good use ofthe event to train students. Besides the tutorial session, which is aimed togive students a general but significant overview on SRF subjects, a studentposter session will be included during the conference.

All students and young researcher have the opportunity to present their workin a student poster session. This is a good chance to get in contact with eachother and to connect our SRF community. The student poster session will beheld on Sunday (June 30th) from 16:00-18:00 in the Rossini Hall. Posters willremain displayed until 20:00 during the welcome reception (18:00-20:00).

Students with grants are expected to present a poster in the student postersession and must place it before 16:00 and remove it after 20:00. For studentswithout a grant this session is optional. In any case, please indicate duringregistration process if you would like to attend the student poster session.

In accordance with the guidelines for publication of contributions, theseposters must also be displayed during the regular poster sessions.

PROCEEDINGS

The SRF2019 proceedings will be published by the JACoW Joint AcceleratorConferences editorial team. To ensure consistency of the conference proceed-ings, all papers have to meet formal criteria, specified by JACoW. For docxfiles you can check these formal criteria yourself using the JACoW Word Validator: http://edit.ipac19.org/upload

The paper submission deadline was Sunday, 23 June, 2019. After this deadline,the Editorial staff will process papers before and during the conference and perform formal paper checks and conversions according to the JACoW publishing requirements. Once an editor is assigned to your paper, your uploaded PDF is checked and, if necessary, formal corrections are done.

The corrected PDF is uploaded together with all changed files into yourconference database profile. You will be informed by e-mail about the statusof your paper. If the status is YELLOW you are required to check the changesmade by the editor. You can download the PDF from SPMS and when you agree with the changes set the paper status to GREEN using the provided link in the e-mail. If you are not satisfied with the changes you can reject the changes but please provide reasons for doing so.

Authors can check the status of their papers via the login to their SRF2019SPMS account or by consulting the electronic dot board at the conference. E-mails will be sent via SPMS whenever a processing dot colour is assigned orchanged.To see the electronic dot board go to: https://oraweb.cern.ch/pls/srf2019/edot.html

Authors with questions are invited to go to the Author Reception located inthe Salon Mainz.

xii SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

TUTORIAL SESSIONS

The SRF2019 tutorial sessions will be held prior to the conference from June 27 – 29 at the HZDR campus.T he tutorials are especially designed for students as well as scientists and engineers new to the SRF field. The audience will have a chance to learn the fundamental knowledge and also the latest trends in the science, technology and application of SRF for particle accelerators. The program agenda is as follows and the slides will be available after the tutorial lectures.

Tutorial Lecture Schedule for SRF201908:30-09:00

thJun 27 , Th. Registration and WelcomeP. Michel (HZDR)

Session 1 09:00-10:30thJun 27 , Th. Basic Principles of RF Superconductivity

G. Ciovati (JLab)thJun 28 , Fr. Superconducting Cavities of Interesting Shapes (Non-elliptical Cavities)

S. De Silva (ODU)thJun 29 , Sa. Beam-cavity Interaction and operational Aspects of SRF Systems with Beam

S. Belomestnykh (FNAL)Coffee Break 10:30-11:00 Session 2 11:00-12:30

thJun 27 , Th. RF Basic and TM CavitiesE. Jensen (CERN)

thJun 28 , Fr. Cavity Processing and Cleanroom TechniquesL. Popielarski (FRIB/MSU)

thJun 29 , Sa. LLRF Controls and RF OperationJ. Branlard (DESY)

Lunch 12:30-13:30 Session 3 13:30-15:00

thJun 27 , Th. Cavity Vertical and Horizontal Test and OperationT. Powers (JLab)

thJun 28 , Fr. Pushing Bulk Nb Limits (High Q, High Gradient, Reliable SRF Accelerators)A. Grassellino (FNAL)

thJun 29 , Sa. Fundamentals of Cryomodule Design and CryogenicsB. Petersen (DESY)

Coffee Break 15:00-15:30 Session 4 15:30-17:00

thJun 27 , Th. High Power Couplers and HOM CouplersE. Kako (KEK)

thJun 28 , Fr. Materials Beyond Bulk NbC. Antoine (Saclay)

thJun 29 , Sa. Methods and Simulation Tools for Cavity DesignH.-W. Glock (HZB)

SRF 19 — Dresden, Germany — June 30th – July 5th, 2019 xiii

TECHNICAL TOURS

Time: 13:00

XFEL Tour in Hamburg (5-6 h away from Dresden)Saturday, 29 June, 13:00 – app. 17:00

(limited to 45 persons)

On Saturday, right before the conference, DESY will offer a guided tour in the European XFEL tunnel, the European XFEL injector hall and the AMTF hall (optional). The tour is offered for free and includes a bus transfer from Hamburg to Dresden on Sunday morning. Please note that the European XFEL tunnel and injector are radiation controlled areas, so you have to register on-site. Please take also into account that the tour is done on foot.

ELBE TourFriday, 05 July, 13:00 – 17:00

On Friday, July 5th the Helmholtz-Center Dresden-Rossendorf offers a guided tour to the ELBE Radiation Source. The tour buses will leave at 1pm from the conference venue and return about 5pm. Lunch bags (optionally vegetarian) will be provided.

ELBE is a user facility utilizing a high-power cw electron beam with currents up to 1.6 mA which is accelerated by a superconducting RF accelerator up to 35 MeV beam energy. This beam is used to drive two free-electron lasers for the mid and far infrared spectral range. A superradiant THz source delivers synchronized broad-band and narrow-band (undulator) radiation in the 100 GHz to 3 THz frequency range.

A superconducting radio frequency (RF) photoelectron injector (SRF gun) is in operation at the ELBE Radiation Source. It is designed to either generate a high-average current cw electron beam with low emittance to drive the ELBE FELs or deliver a high bunch charge (up to 1nC) for the ELBE THz and particle sources.

Meeting-Point: Lobby of the Hilton Dresden Hotel

[https://www.hzdr.de/db/Cms?pNid=145]

[https://www.hzdr.de/db/Cms?pNid=2804]

xiv SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

INDUSTRIAL EXHIBITION

The Conference will combine the scientific program with an industrial exhibition which will be held next to the plenary room together with the coffee breaks, from Monday 01 to T hursday 04 July 2019.

11 Companies will present their products, services and the latest developments in the fields of surface treatment, materials, coatings, surface analysis, imaging and microscopy, vacuum systems.

This free access exhibition is aimed at providers of research equipment and materials, publishers working in the scientific community and employers of science graduates.

Days & hours

Welcome Reception: Sunday 30 June 18:00 – 20:00Exhibition: Monday 01 July – Thursday 04 July 8:00 – 18:00

oupgr

SRF 19 — Dresden, Germany — June 30th – July 5th, 2019 xv

auth

or

Catering

Poster

Session& Catering

Plenum

Clo

ackr

oo

m

WC

Piano Bar

Foyer

Rossini

Salo

n B

erlin

Saal 1 + 2

Salo

n F

ran

kfu

rt +

Dü

ssel

do

rf

Hotel Garten

Poster

Session

&

Catering

Ro

om

Salo

n w

eim

ar

Spea

kers

Rea

dy

Ro

om

Salo

n M

ain

z

Catering

Exhibitors

# 01 PINK# 02 SAES GETTERS# 03 BARTINGTON INSTR.# 04 RI RESEARCH INSTR.# 05 NINGXIA ORIENT# 06 STRUCK INNOV. SYSTEME# 07 CANON ELECTRON# 08 EL-SPEC# 09 ULVAC# 10 PFEIFFER VACUUM# 11 TOKYO DENKAI

01

02

04

05

10

07 08 09

11

03

06

Companies (last update: 12.06.2019) Booth Number

PINK GmbH Vakuumtechnik 01SAES Getters S.p.A. 02Bartington Instruments Ltd. 03RI Research Instruments GmbH 04NINGXIA ORIENT TANTALUM INDUSTRY CO., Ltd. 05Struck Innovative Systeme GmbH 06CANON ELECTRON TUBES & DEVICES CO., Ltd. 07el-spec GmbH 08Ulvac, Inc. 09Pfeiffer Vacuum GmbH 10Tokyo Denkai Co., Ltd. 11

INDUSTRIAL EXHIBITION

LAYOUT OF VENUE

xvi SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

ContentsMOFAA — Facilities 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

MOFAA1 LCLS-II: SRF Scope, Status, Issues and Plans . . . . . . . . . . . 4MOFAA2 Operation of the European XFEL Towards the Maximum Energy 4MOFAA3 The FRIB SC-Linac - Installation and Phased Commissioning . 5MOFAA4 ESS: SRF Systems, Overview and Status . . . . . . . . . . . . . . 5

MOFAB — Facilities 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6MOFAB1MESA: The Mainz Energy Recovering Superconducting Accel-

erator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6MOFAB2 SRF Status of the SHINE Project at Shanghai . . . . . . . . . . . 6MOFAB3 SRF Status of the RAON Heavy Ion Accelerator Project . . . . . 6MOFAB4 Overview and SRF Requirements of the CiADS Project . . . . . 7MOFAB5 Status and Challenges of the MYRRHA SRF Linac . . . . . . . . 7MOFAB6 More than 15 Years of CW SRF Operation at ELBE . . . . . . . . 8

MOKN — Key Note Talk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9MOKN1 Scientific Applications Using High Repetition Rate Hard X-Ray

FELs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9MOP — Monday Poster Session . . . . . . . . . . . . . . . . . . . . . . . . . 10TUFUA — Fundamental 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

TUFUA1 The Field-Dependent Surface Resistance of Doped Niobium:New Experimental and Theoretical Results . . . . . . . . . . . . . 44

TUFUA2 Overview of Progress in High Q and High G in Niobium Cavities 44TUFUA3 Development of a Qualitative Model for N-Doping Effects on

Nb SRF Cavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44TUFUA4 New Insights on Nitrogen Doping . . . . . . . . . . . . . . . . . 45TUFUA5 Recent Development on Nitrogen Infusion Work Towards

High Q and High Gradient . . . . . . . . . . . . . . . . . . . . . . . 45TUFUA6 Surface Analysis of Niobium After Thermal/Gas Treatments

via Samples - Review . . . . . . . . . . . . . . . . . . . . . . . . . . 45TUFUA7 Review of Muon Spin Rotation Studies of SRF Materials . . . . 46

TUFUB — Fundamental 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47TUFUB1Direct Correlation of State of the Art Cavity Performance With

Surface Nb Nano-Hydrides Cutouts Observed via Cryogenic AFM 47TUFUB2 New Insight on RF Field Amplitude and Frequency Depen-

dence of Vortex Surface Resistance . . . . . . . . . . . . . . . . . . 47TUFUB3 Mapping Flux Trapping in SRF Cavities to Analyze the Impact

of Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47TUFUB4 Microscopic Investigation of Flux Trapping Sites in Bulk Nb . . 47TUFUB5 Effects of Static Magnetic Fields on a Low-frequency TEM

Class Superconducting Cavity . . . . . . . . . . . . . . . . . . . . 48

1SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

Co

nte

nts

Co

nten

ts

TUFUB7 Measurement of Surface Resistance Properties with CoaxialResonators - Review . . . . . . . . . . . . . . . . . . . . . . . . . . 48

TUFUB8 CVD Coated Copper Substrate SRF Cavity Research at CornellUniversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

TUKN — Key Note Talk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50TUKN1 Pros and Cons of Laser-Plasma Accelerators: Where Are the

Limits, and Will LPA Compete With SRF . . . . . . . . . . . . . . . 50TUP — Tuesday Poster Session . . . . . . . . . . . . . . . . . . . . . . . . . 51WETEA — Technology 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

WETEA1 ESS Technology Development at IPNO and CEA Paris-Saclay . 86WETEA2 SRF Cryomodules for PIP-2 at Fermilab . . . . . . . . . . . . . . 86WETEA3 Status of the IFMIF-EVEDA Superconducting Linac . . . . . . . 86WETEA4 Production and Performance of LCLS-II Cryomodules . . . . . 86WETEA5 FRIB Cavity and Cryomodule Performance, Comparison With

the Design and Lessons Learned . . . . . . . . . . . . . . . . . . . 86WETEA6 Successful Beam Commissioning in STF-2 Cryomodules for ILC 87

WETEB — Technology 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88WETEB1 Development of SC-QWR and Cryomodule for Low-Beta Ion

Accelerator at RIKEN RIBF . . . . . . . . . . . . . . . . . . . . . . 88WETEB2 Identifying Specific Cryomodule and Cleanroom Particulate

Contamination: Understanding Legacy Issues and ProvidingNew Feedback Standards . . . . . . . . . . . . . . . . . . . . . . . 88

WETEB3 Diagnosing Particular Operational Cavity Fault Causes UsingTime Domain RF Waveforms . . . . . . . . . . . . . . . . . . . . . 88

WETEB4 Virtual SRF Cavity: Testing SRF Cavity Support Systems With-out the Hassle of Liquid Helium and Klystrons . . . . . . . . . . . 89

WETEB5 Modular Digital Low Level Radio Frequency Control (LLRF)for CW Operation at ELBE . . . . . . . . . . . . . . . . . . . . . . . 89

WETEB6 Active Suppression of Microphonics Detuning in High QLCavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

WETEB7 A Fast Reactive Tuner Based on Ferroelectrics for Supercon-ducting Cavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

WETEB8 The Fundamental Power Coupler for CEPC Booster Cavity . . 90WETEB9 Design Development for the 1.5 GHz Couplers for BESSY VSR . 90

THFUA — Fundamental 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91THFUA1 RF Characterization of an S-I-S Multilayer Sample . . . . . . . 91THFUA2 Evaluation of the Superconducting Characteristics of Multi-

Layer Thin-Film Structures of NbN/SiO2 on Pure Nb Substrate . 91THFUA3 Material and Superconducting Properties of NbTiN/AlN Mul-

tilayer Films . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92THFUA4 Field-Dependent Nonlinear Surface Resistance and Its Opti-

mization by Surface Nano-Structuring of the SRF Cavities . . . . 92THFUA5 Field Limitation in Nb3Sn Cavities . . . . . . . . . . . . . . . . . 92THFUA6 Nb3Sn Films for SRF Cavities: Genesis and RF Properties . . . 93

2 SRF 19 — Dresden, Germany — June 30th – July 5th, 2019

Co

nte

nts

THFUA7 RF Performances of Nb3Sn Coatings on a Copper Substratefor Accelerating Cavities Applications . . . . . . . . . . . . . . . . 93

THFUB — Fundamental 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94THFUB1 Nb3Sn at Fermilab: Exploring Performance . . . . . . . . . . . 94THFUB2 Progress With Nb Hipims Films on 1.3 GHz Cu Cavities . . . . 94THFUB3Nb/Cu Coatings Characterization in HiPIMS With Biased Sub-

strate and Application of a Positive Pulse . . . . . . . . . . . . . . 94THFUB4 Effect of Inhomogeneous Disorder on the Superheating Field

of SRF Cavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95THFUB5 Employing SRF to Boost Coherence of 3D Quantum Systems . 95

THHT — Hot Topic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96THHT1 Maximizing Peak Surface Fields - Time Barrier vs. Surface Barrier 96

THP — Thursday Poster Session . . . . . . . . . . . . . . . . . . . . . . . . 97FRCAA — Cavities 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

FRCAA1 Overview of SRF Deflecting and Crabbing Cavities . . . . . . . 135FRCAA2 Balloon Single Spoke Resonator - A New Variant for Reduced

Multipacting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135FRCAA3 Industrial Cavity Production: Lessons Learnt to Push the

Boundaries of Nitrogen-Doping . . . . . . . . . . . . . . . . . . . 135FRCAA4 Progress in SRF CH-Cavities for the HELIAC CW Linac at GSI . 136FRCAA5 SRF Activities and Progress at IHEP . . . . . . . . . . . . . . . . 136FRCAA6 Investigation on 1, 3 and 9-Cell SRF Elliptical Cavities Made

of Large Grain Niobium . . . . . . . . . . . . . . . . . . . . . . . . 137FRCAB — Cavities 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

FRCAB1 HF-Free Bi-Polar Electropolishing for Application on Multi-Cell Elliptical Cavities . . . . . . . . . . . . . . . . . . . . . . . . . 138

FRCAB2 Electrodeposition of Copper Applied to the Manufacture ofSeamless SRF Cavities . . . . . . . . . . . . . . . . . . . . . . . . . 138

FRCAB3 The Design of an Automated High-Pressure Rinsing Systemfor SRF Cavity and the Outlook for Future Automated Clean-room on Strings Assembly . . . . . . . . . . . . . . . . . . . . . . . 139

FRCAB4Development of High Intensity, High Brightness, CW SRF GunWith Bi-Alkali Photocathode . . . . . . . . . . . . . . . . . . . . . 139

FRCAB5 Performance of 112 MHz SRF Gun at BNL . . . . . . . . . . . . 139FRCAB6 The Effect of Helium Processing and Plasma Cleaning for Low

Beta HWR Cavity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140FRCAB7 Plasma Processing of LCLS-II Cavities . . . . . . . . . . . . . . . 140FRCAB8 Systematic Studies of the Second Sound Method for Quench

Detection of Superconducting Radio Frequency Cavities . . . . . 140Author List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

SRF 19 — Dresden, Germany — June 30th – July 5th, 2019 3

01Ju

l–M

on

01-Jul-19 08:20 – 10:00 AuditoriumMOFAA — Facilities 1

Chair: J. Knobloch (HZB)

MOFAA108:20 30

LCLS-II: SRF Scope, Status, Issues and PlansM.C. Ross (SLAC)The Linac Coherent Light Source II (LCLS-II) project requires the assem-bly, test, and installation of 37 cryomodules (CM) in order to deliver a4 GeV CW electron beam to the FEL undulators for production of both hardand soft X-ray pulses at a repetition rate of up to 1 MHz. SRF cavity per-formance in the 30+ tested CM exceeds gradient and cryogenic dynamicheat-load requirements (set at 16 MV/m and 10 W resp). In this talk wepresent microphonics, shipping, magnetic-flux exclusion, and field emis-sion performance. The US funding agency, DOE, has recently approved anadditional 20 CM for the extension of LCLS-II to 8 GeV. This paper will alsoinclude initial cavity and heat-load performance results for the extensionproject, LCLS-II-HE.

MOFAA208:50 20

Operation of the European XFEL Towards the Maximum EnergyM. Omet, V. Ayvazyan, J. Branlard, S. Choroba, W. Decking, V.V. Katalev,D. Kostin, L. Lilje, P. Morozov, Y. Nachtigal, H. Schlarb, V. Vogel, N. Walker,B. Yildirim (DESY)After the initial commissioning of the available 25 radio frequency (RF) sta-tions of the European XFEL (RF gun, A1, AH1 and stations A2 through A23)a maximum electron beam energy of 14.5 GeV was achieved, 3 GeV shortof the design energy of 17.5 GeV. In order to tackle this problem, the Maxi-mum Gradient Task Force (MGTF) was formed. In the scope of the workof the MGTF, RF stations A6 through A25 (linac L3) were systematicallyinvestigated and voltage-limiting factors of the SRF accelerating modulesand their RF distribution system were identified and improved. As a re-sult, the design electron beam energy was exceeded at 17.6 GeV on the18.7.2018. Beside this an overview over the regular RF operation at theEuropean XFEL is given.


01Ju

l–M

on

MOFAA309:10 30

The FRIB SC-Linac - Installation and Phased CommissioningJ. Wei, H. Ao, S. Beher, B. Bird, N.K. Bultman, F. Casagrande, D. Chabot,W. Chang, S. Cogan, C. Compton, J. Curtin, K.D. Davidson, E. Daykin, K. Ell-iott, A. Facco, A. Fila, V. Ganni, A. Ganshyn, P.E. Gibson, T. Glasmacher,I. Grender, W. Hartung, L. Hodges, K. Holland, H.-C. Hseuh, A. Hussain,M. Ikegami, S. Jones, T. Kanemura, S.H. Kim, P. Knudsen, M.G. Konrad,J. LeTourneau, Z. Li, S.M. Lidia, G. Machicoane, P. Manwiller, F. Marti,T. Maruta, E.S. Metzgar, S.J. Miller, D.G. Morris, C. Nguyen, K. Openlan-der, P.N. Ostroumov, A.S. Plastun, J.T. Popielarski, L. Popielarski, J. Priller,M.A. Reaume, H.T. Ren, T. Russo, K. Saito, M. Shuptar, D.R. Victory,R. Walker, X. Wang, J.D. Wenstrom, M. Wright, M. Xu, T. Xu, Y. Yamazaki,Q. Zhao, S. Zhao (FRIB) K. Dixon, M. Wiseman (JLab) A. Facco (INFN/LNL)K. Hosoyama (KEK) M.P. Kelly (ANL) R.E. Laxdal (TRIUMF)The Facility for Rare Isotope Beams (FRIB) superconducting (SC) driverlinac is designed to accelerate all stable ions including uranium to ener-gies above 200 MeV/u primarily with 46 cryomodules containing 324 quar-ter-wave resonators (QWR) and half-wave (HWR) resonators. With thenewly commissioned helium refrigeration system supplying liquid heliumto the QWR and solenoids, heavy ion beams including Ne, Ar, Kr and Xewere accelerated to the charge stripper location above 20 MeV/u with thefirst linac segment consisting of 15 cryomodules containing 104 QWRsof β=0.041 and 0.085 and 39 solenoids. Installation of cryomodules withβ=0.29 and 0.53 HWRs is proceeding in parallel. Development of β=0.65elliptical resonators is on-going supporting the FRIB energy upgrade to400 MeV/u. This paper summarizes the SC-linac installation and phasedcommissioning status that is on schedule and on budget to the FRIBproject.

MOFAA409:40 20

ESS: SRF Systems, Overview and StatusP. Pierini (ESS)We report the status of the testing of SRF cryomodule at the ESS moduletest facilities and the preparation activities for the installation and com-missioning of the ESS SRF Linac.


01Ju

l–M

on

01-Jul-19 10:30 – 12:30 AuditoriumMOFAB — Facilities 2

Chair: D. Reschke (DESY)

MOFAB110:30 20

MESA: The Mainz Energy Recovering Superconducting AcceleratorF. Hug, D. Simon, T. Stengler, C.P. Stoll, S.D.W. Thomas (KPH) K. Aulen-bacher (HIM)The Mainz Energy-Recovering Superconducting Accelerator (MESA) iscurrently under construction at Johannes Gutenberg-University Mainz. Itis a mulit-turn ERL for particle and nuclear physics experiments. As thecenterpiece for acceleration a turn-key solution was chosen. Two modi-fied ELBE/Rossendorf-type cryomodules will accelerate the electrons upto 25 MeV per turn. The modules will be operated in cw at an acceleratinggradient of 12.5 MV/m. The modifications comprise of an integration ofa piezo tuner system and a better thermal connection of the HOM anten-nas for allowing high beam current in cw operation. Site acceptance testsof both modules have been carried out at the Helmholtz Institute Mainz(HIM) and by now the first cryomodule was successfully operated at de-sign gradient and could be accepted. This talk will cover the experienceswith a turn-key solution made by industry and will show the results of thesite acceptance tests.

MOFAB210:50 20

SRF Status of the SHINE Project at ShanghaiH.T. Hou (SINAP) J.F. Chen, X. Hu, Y. Liu, Z.Y. Ma, S. Sun, D. Wang, L. Yin,S.J. Zhao, Y.B. Zhao (SARI-CAS)The talk will mainly introduce the progress of the SHINE project in China.It is scheduled to build SHINE project in seven years which includes a su-perconducting rf acceleractor based on TESLA technology. From 2018,SHINE started the prototypes R&D in China, including not only the cav-ities fabrication, but also the surface treatment methods to reach high Qperformance. The preparition of test facility will be introduced, too. Theplan and latest results will be reported in the talk.

MOFAB311:10 20

SRF Status of the RAON Heavy Ion Accelerator ProjectH.C. Jung, H. Jang, Y. Kim, Y.K. Kwon (IBS)Quarter-wave resonators (QWR), Half-wave resonators (HWR)are adoptedfor the low energy superconducting linear accelerator of RAON, two typesSingle spoke resonators(SSR type1, SSR type2) are for the High energy.The performance tests for the prototypes of QWR, HWR cryomodules arecarried and the designed goals are achieved. About 130 QWR/HWR cav-ities and 56 modules shall be produced and tested within 2020. For thecryogenic tests, facilities are constructed with 5 module-test bunkers and5 cavity-test pits. First one cryomodule with 3 SSR1 cavities will be testedin this year and two cryomodules with 6 SSR2 cavities will be tested withinthe first quarter of the next year.


01Ju

l–M

on

MOFAB411:30 20

Overview and SRF Requirements of the CiADS ProjectY. He, Q. Chen, Z. Gao, H. Guo, G. Huang, Y.L. Huang, T.C. Jiang, C.L. Li,S.H. Liu, T. Tan, Y.Q. Wan, F.F. Wang, J.Q. Wu, W.M. Yue, B. Zhang,J.H. Zhang, S.H. Zhang, S.X. Zhang (IMP/CAS) J.P. Dai, F.S. He, Z.Q. Li,W.M. Pan (IHEP) T.C. Jiang (University of Chinese Academy of Sciences)Chinese initiative Accelerator Driven System started constructing in 2018.It consists a superconducting linac with 500 MeV and 5 mA; an LEB coolantfast reactor with 7.5 MW. The first beam coupling with reactor will be in2024. The sc linac employed 5 families of superconducting resonators, twotypes of HWRs (β=0.1 and β=0.19), one type of double spokes (β=0.42) andtwo types of ellipticals (β=0.62 and β=0.82). The whole system will oper-ate in 2 K. A space has been reserved for future upgrading to 1 GeV. As ademo of front-end of ADS, the CAFe (China ADS Front-end demo linac)has been developed and commissioned to verify the SRF techniques, highpower CW beam and RAMI. 45 kW proton beam has been delivered to thedump and lasted more than 100 hours at the beginning of 2019. Accordingto the operation experience, the challenge is the stability and performanceof cavities under the heavy beam loading, some phenomenas have beenobserved. Up to now, the design of bulk Nb cavities have been finishedand the prototype fabrication is on going. The techniques of Nb/Cu cavityand Nb3Sn are also developed in IMP for the future project of ADS.

MOFAB511:50 20

Status and Challenges of the MYRRHA SRF LinacD. Vandeplassche (SCK•CEN)The MYRRHA project aims at realizing a demonstrator Accelerator DrivenSystem (ADS), of which the essential goal is to provide an optimized pathtowards transmutation. This allows to greatly reduce the burden of longlived nuclear waste originating from fission power plants. The specific ADSapplication requires a CW driver linac with an exceptionally high beam-MTBF of 250 hours, a beam failure corresponding to a beam trip longerthan 3 s. The key feature for obtaining this level of reliability is fault tol-erance. It is essentially provided through the serial redundancy that thehighly modular structure of the superconducting linac combined with ad-equate operational margins offers. Phase 1 of MYRRHA will see the con-struction of the 100 MeV linac based on one family of β=0.37 supercon-ducting 2-gap spoke cavities. The evaluation of the fault tolerance mecha-nism will be a major topic of this linac’s exploitation.


01Ju

l–M

on

MOFAB612:10 20

More than 15 Years of CW SRF Operation at ELBEA. Arnold, M. Freitag, U. Lehnert, P. Michel, P. Murcek, Ch. Schneider, J. Tei-chert, R. Xiang (HZDR)ELBE is a compact, accelerator-driven photon and particle source. Since2001 it is operated as a user facility, providing more than 5500 hours ofbeam time each year. The electron accelerator is based on four supercon-ducting 9-cell TESLA cavities that are driven in full CW operation to accel-erate an average current of 1 mA up to beam energies of 40 MeV. The firstpart of the talk will summarize our experiences of operating TESLA cavi-ties in CW. In detail, this includes their performance and attempts to im-prove it, as well as investigations on limitations. Additionally, we will dis-cuss several issues that are related to the high average RF as well as beampower and we will present appropriate measures to protect the machine.In this regard, a resonant ring for RF component tests up to 100 kW was setup. The second part of the talk will focus on the development and opera-tion of our SRF guns that are designed to produce short bunches with highcharges and repetition rates of 1 MHz and beyond. Recently, SRF gun IIwas successfully transferred into routine user operation and delivers nowmore than 200 pC at 100 kHz to the experiment. First convincing resultswill be presented.


01Ju

l–M

on

01-Jul-19 12:30 – 13:00 AuditoriumMOKN — Key Note TalkChair: D. Reschke (DESY)

MOKN112:30 30

Scientific Applications Using High Repetition Rate Hard X-Ray FELsT. Tschentscher (EuXFEL)Hard X-ray free-electron lasers (FEL) present one of the most challengingapplications of electron accelerators. European XFEL is one of these in-stallations providing up to ∼30.000 bunches per second, more than a fac-tor 100 higher than other facilities. High repetition rate FEL experimentsallow to open new science opportunities and thus drive the accelerator de-velopment. These facilities rely on SRF technology to enable high repeti-tion rates, either by using pulsed RF (FLASH, European XFEL) or so-calledcontinuous-wave (cw) RF (LCLS-II, SHINE). European XFEL has starteduser operation in 2017 after 8 yrs of construction. The facility is designedto serve several science instruments quasi-simultanously using its deliveryof up to ∼30.000 bunches per second using a 10 Hz burst pattern. Thesebunches can be distributed to presently 3 (future 5) FEL sources serving6 to 10 science instruments. The talk will cover the scientific motivationfor hard X-ray high repetition rate FELs, introduce the current facility sta-tus, and highlight results from first experiments using high repetition rateX-ray delivery. Differences between pulsed and cw beam delivery will bediscussed.


01Ju

l–M

on

01-Jul-19 14:30 – 18:00 Poster AreaMOP — Monday Poster Session

MOP001 Nb3Sn Multitarget Sputtering for Nb SRF CavitiesN. Schäfer, L. Alff, M. Major (TU Darmstadt)Nowadays Nb is commonly used for superconducting radio frequency(SRF) cavities. Nb3Sn is a promising thin film material for SRF cavities as itcan empower the cavity to operate at higher acceleration fields and highertemperatures. This is also achievable by a higher quality factor since thesurface resistivity (RS) is lower with respect to Nb-only cavities at radiofre-quency. Several approaches could be used for deposition of Nb3Sn thinfilm (e.g. sputtering, evaporation, and CVD. The applicability for cavitieswas demonstrated for several processes with their respective disadvan-tages. Nb3Sn is either synthesized by a deposition of Sn on the Nb cavity ora stoichiometric deposition of Nb and Sn. The right stoichiometry is essen-tial to use the full potential of the Nb3Sn material properties while understoichiometric layers have still improved properties. A new modificationto the sputtering process is made in the Advanced Thin Film Technologygroup without a subsequent annealing step to improve the stoichiometryof the layer.

MOP002 Low Temperature Heat Treatment of Nb/Sn Multilayers and Nb/Cu/SnMultilayersT. Tan, Q.W. Chu, M. Lu, F. Pan, R.X. Wang (IMP/CAS)Copper-based thin film SRF cavities have showed good RF performance,advanced thermal conductivity, and superior mechanical stabilities.Nb3Sn thin film is the most promising candidate beyond bulk Nb for SRF.How to combine the benefits from both ends is now questioning the thinfilm SRF researchers. Direct tin diffusion technique is not suitable forfabricating Nb3Sn/Cu cavities because its high reaction temperature (>1100oC). However, at low temperature, the mobility of Sn in Nb is ex-tremely small. There are two ways to solve this problem. The first solutionis alternative Nb/Sn multilayer structure, which can reduce the diffusionlength and increase the activity, and result in an acceptable reaction time.The other option is adding copper layer in the multilayer structure, whichsignificantly increase the mobility and forms bronze/Nb3Sn bilayer struc-ture in the end. The SRF group of IMP has successfully deposited Nb/Sncopper/Sn/Nb multilayer structures on copper substrates. Low temper-ature annealing has been performed on both structures to obtain Nb3Snthin film on copper. The Nb3Sn films’ properties and their relationship toannealing parameters are studied.

MOP003 Development of Nb3Sn Cavity Coating at IMPZ.Q. Yang, H. Guo, Y. He, C.L. Li, T. Tan, P.R. Xiong, S.H. Zhang, S.X. Zhang(IMP/CAS)The A15 superconductor Nb3Sn is one of the most promising alternativematerials to standard niobium for SRF applications. In this paper, we re-port our progress in the development of Nb3Sn cavity coating by vapordiffusion method at IMP. The evolutionary process of nucleation was an-alyzed. Influence of SnCl2 partial pressure inhomogeneity was studied.


01Ju

l–M

on

Less-nuclear zones were found on the surfaces of nucleation samples. TheNb3Sn film structure and composition were investigated and analyzed. Inlight of knowledge obtained above, the coating process was optimized. Fi-nally, both 1.3 GHz and 650 MHz single cell cavities were coated and verti-cally tested both at 4 K and 2 K. Effect of low temperature baking (1000oCfor 48 hs) on the RF performance of Nb3Sn cavity was studied. After bak-ing, the Q drop in the low field region was eliminated and the Q in theintermediate field region was increased 8 times. The Q was 10 times largerthan that of the Nb cavity at 4.2 K even in the case of the ambient fieldlarger than 20 mGs. This study shows that the low temperature baking isan effective enrichment to the post treatment of the Nb3Sn cavity.

MOP004 Preparation of Pb-Photocathodes at National Center for Nuclear Re-search in Poland – State of the ArtJ. Lorkiewicz, I. Cieslik, P.J. Czuma, A.M. Kosinska, R. Nietubyć (NCBJ)J.K. Sekutowicz (DESY)R&D activities related to preparation of the superconducting Pb photo-cathode layer on niobium substrate are ongoing at the National Centre forNuclear Research (NCBJ) in cooperation with DESY, HZDR, HZB, BNL andother research institutes. The activities are part of the R&D program atDESY for the cw-upgrade of E-XFEL and for the newly approved free elec-tron laser facility PolFEL to be built and operated at NCBJ. The optimiza-tion results obtained for the lead deposition on niobium and smoothingof the coated layers are reported. The photocathodes samples were testedfor their surface morphology, microstructure and quantum efficiency interms of the impact on the operation of all-superconducting RF electroninjector, proposed for both facilities.

MOP005 Development of a Solenoid Magnetron Based Hybrid Physical ChemicalVapor Deposition (HPCVD) System for Deposition of SuperconductingThin Films on 3D SubstratesN. Misra, R. Valizadeh (STFC/DL/ASTeC) , R. Valizadeh (Cockcroft Institute)In this work we report a novel approach towards coating MgB2 on 3D sur-faces using Solenoid Magnetron based Hybrid Physical Chemical VaporDeposition approach. The setup comprises of a Mg rod (1.6 mm diameter)serving as the sputtering target and confined within a metallic cylinder,the three dimensional substrate. The substrate in turn is surrounded by asolenoid coil powered by a DC power supply (∼80 V, 2 A) to provide a uni-form magnetic field. One gas line is connected from the base to introduceH2 gas to initiate the precursor decomposition reaction within the plasma.Boron is sourced from high purity BBr3 injected into the system using highpurity Ar as carrier gas. The plasma generated from Mg sputtering decom-poses BBr3 in presence of H atoms to liberate B in atomic form, followed bychemical reaction between Mg and B and ultimate deposition of MgB2 onthe substrate. The entire system is maintained at a temperature of 150oCto ensure uniform deposition and high adhesion of the coating to the sub-strate surface. Parameters such as the Ar and H2 flow rate, input power anddeposition time are varied to optimize the conditions necessary to main-tain the desired Mg/B atomic ratio of 1:2.


01Ju

l–M

on

MOP006 PVD Deposition of Nb3Sn on Copper and Sapphire SubstrateR. Valizadeh, A.N. Hannah, O.B. Malyshev (STFC/DL/ASTeC) T. Jungin-ger, O.B. Malyshev (Cockcroft Institute) T. Junginger (TRIUMF) G.B.G. Sten-ning (STFC/RAL/ISIS) D. Turner (Cockcroft Institute, Lancaster University)D. Turner (STFC/DL)Nb3Sn is superconductor with a critical temperature of 18 K which ishigher than that of Nb (9.3 K). Hence at 4 K has RF resistance of an order ofmagnitude lower than that of Niobium which lead to quality factor abovethose of Nb. In recent years there has been an extensive effort convertingNb cavity into Nb3Sn. In this study we report on PVD deposition of Nb3Snsputtered directly from a alloy target at various temperature ranging fromroom temperature up to 650oC with an without thick Nb layer depositedon copper and sapphire substrate producing a multilayer of Cu/Nb/Nb3Snor Cu/Nb3Sn. The dependence of superconducting properties of the totalstructure on deposition parameters is been determined. The films havebeen characterized via SEM, TEM, XRD, RRR measurements and SQUIDmagnetometer. Analysis showed that the composition in both room andelevated temperature was within the desired stoichiometry of 24-25 at%,however the superconducting properties was only observed for elevatedtemperature deposition or post annealing at 650oC. The critical tempera-ture was determined to be 17.8 K.

MOP007 400 MHz Seamless Copper Cavity in the Framework of FCC StudyO. Azzolini, G. Keppel, C. Pira (INFN/LNL)In the framework of the FCC study the production of 400 MHz copper cav-ities is one of the key challenges for the development of more efficientsuperconducting RF cavities. Any progress on substrate manufacturingand preparation will have an immediate impact on the final RF perfor-mance, as it was demonstrated by the seamless cavities produced for theHIE-ISOLDE project. Spinning is a potential alternative to conventionalproduction methods of copper single and multi-cells. In this work is pre-sented the first 400 MHz copper SRF cavity prototype produced via Spin-ning at Laboratori Nazionali di Legnaro of INFN. The production process isexplained starting from a copper foil of 1000 mm diameter and 4mm thickto arrive to a seamless 400 MHz cavity. Moreover, the metrology of the cav-ity and the analysis of the influence of intermediate thermal treatmentsamong each steps of cold work are shown.

MOP008 Performance-Limiting Imperfections in Nb3Sn Coatings for SRF CavityApplications: Grain Boundary (GB) SegregationsJ. Lee, K. He, Z. Mao, D.N. Seidman (NU) D.L. Hall, M. Liepe (Cornell Uni-versity (CLASSE)) J. Lee, S. Posen, T. Spina (Fermilab) D.N. Seidman (NU-CAPT)We report on analyses of grain-boundary (GB) segregation behavior ofNb3Sn coatings for SRF applications using atom-probe tomography (APT)and transmission electron microscopy (TEM). We find Sn segregation atGBs at the level 10-20 atoms/nm2 with ∼3 nm of a width and the max-imum concentration of ∼35 at.% Sn in some Nb3Sn samples, indicatingthat GBs are the principle paths for Sn-diffusion to Nb substrates. GB seg-


01Ju

l–M

on

regation of Sn is not observed in Nb3Sn coatings from high-performanceNb3Sn cavities, indicating that Sn segregation can cause the degradationof the Q-factor. The amount of Sn segregation is correlated with two fac-tors: (i) Sn supply and (ii) temperature, which may affect the overall kinet-ics, including GB diffusion and the interfacial reaction at Nb3Sn/Nb. Wedemonstrate that Sn segregation is mitigated by reducing the Sn supplyand increasing the temperature of Nb substrates; high-performance of aNb3Sn single-cell cavity is achieved using an optimized processing proce-dure. Current research demonstrates that Sn segregation at GBs in Nb3Sncan be controlled by specific growth parameters, which provide a conduitfor fabricating high-performance Nb3Sn SRF cavities.

MOP009 Performance-Limiting Imperfections in Nb3Sn Coatings for SRF CavityApplications: Formation of Patchy Regions With Thin GrainsJ. Lee, K. He, Z. Mao, D.N. Seidman (NU) J. Lee, S. Posen, Y. Trenikhina (Fer-milab) D.N. Seidman (NUCAPT)We report microstructural analyses on the causes of the formation of thepatchy regions in Nb3Sn coatings on Nb for SRF cavity applications usingTEM and EBSD. Patchy regions with large thin grains in Nb3Sn coatingscause significant degradation of the Q-factor and quenches at a low accel-erating field. The formation of thin grains is correlated with two factors:Sn supply and orientation relationships at Nb3Sn/Nb interfaces. In casethe Sn supply is small, thin grains begin to form and a specific orientationrelationship at Nb3Sn/Nb is frequently observed in the thin grains usingTEM. Thin grains with specific orientation relationships: Nb3Sn (120)//Nb(111) and Nb3Sn (002)//Nb (011), have a large lattice mismatch (12.3%)between Nb (011) and Nb3Sn (002), and a high density of misfit disloca-tions is observed at the interfaces utilizing TEM images. The high densityof misfit dislocations at the interfaces probably decreases the mobility ofthe Nb3Sn/Nb interfaces, resulting in the thin-grains. A critical amount ofSn supply and anodization of Nb substrates are suggested to prevent theformation of patchy regions with thin-grains in Nb3Sn coatings.

MOP010 Ab Initio Calculations on the Growth and Superconducting Properties ofNb3SnN. Sitaraman, T. Arias (Cornell University) M. Liepe, R.D. Porter (CornellUniversity (CLASSE))We present results on the application of ab initio methods to importanttopics in Nb3Sn SRF physics. We propose a theory for the growth mecha-nism of Nb3Sn growth on a thick oxide, explaining the puzzling disappear-ing droplet behavior of Sn on Nb oxide and suggesting how in general anoxide layer could react with Sn to produce a Nb3Sn layer of similar thick-ness and uniformity. Using Nb3Sn antisite defect formation and interac-tion energies calculated with density functional theory (DFT), we extendthe Nb-Sn phase diagram to lower temperatures than have been studiedexperimentally. We show that 25% Sn stoichiometry is stable at low tem-peratures, and explore the possibility of Nb3Sn growth from solution atroom temperature. Finally, we calculate the phonon spectral function forstoichiometric, tin-poor, and tin-rich Nb3Sn. Based on these calculations


01Ju

l–M

on

we determine Tc as a function of stoichiometry and more generally as afunction of the two antisite defect concentrations. As tin-rich Nb3Sn ex-ists not in bulk but in microscopic regions around defects such as grainboundaries, its properties are difficult to measure experimentally but mayplay a key role in determining cavity performance.

MOP011 High Frequency Nb3Sn CavitiesR.D. Porter, M. Liepe, J.T. Maniscalco (Cornell University (CLASSE))Niobium-3 Tin (Nb3Sn) is an alternative material to Nb for SRF cavities.This material is capable of higher temperature operation and has high the-oretical maximum accelerating gradients. Cornell University is a leader inthe development of this material for SRF applications, and current Nb3Sn1.3 GHz single cells produced at Cornell achieve quality factors above 1010

at 4.2 K at medium fields, far above what can be reached with niobium.Most of the recent Nb3Sn cavity development has been done at 1.3 GHz.In this paper, we present new results from Nb3Sn cavities at 2.6 GHz and3.9 GHz. We compare relative cavity performance and flux trapping sen-sitivities, and extract frequency dependencies. Results show that the fre-quency can be increased without degrading the performance of the cavi-ties, opening the path towards a new generation of compact and efficientSRF cavities for a wide range of future applications.

MOP012 Optimization of Nb3Sn Coatings for SRF CavitiesR.D. Porter, M. Liepe, J.T. Maniscalco (Cornell University (CLASSE))Niobium-3 Tin (Nb3Sn) is a promising alternative material for SRF cavi-ties, capable of twice the operating temperature and theoretically twice theaccelerating gradient of niobium cavities. Current state-of-the-art Nb3Sncavities meet specifications of current major accelerator projects, but sig-nificant further improvements in quality factors and accelerating gradi-ents are possible. Here we investigate sources of surface resistance, in-cluding what appears to be two-gap superconductivity, and the quenchmechanism. We make changes to the Nb3Sn coating process and show theimpacts on quality factor and accelerating gradients.

MOP013 Reducing Surface Roughness of Nb3Sn Through Chemical PolishingTreatmentsH. Hu, M. Liepe, R.D. Porter (Cornell University (CLASSE))Niobium-3 tin (Nb3Sn) is a promising alternative material for SRF cav-ities, with theoretical limits for critical temperatures and superheatingfields reaching twice that of conventional Nb cavities. However, currentlyachievable accelerating gradients in Nb3Sn cavities are much lower thantheir theoretical limit. One limitation to the maximum accelerating gradi-ent is surface magnetic field enhancement caused by the surface rough-ness of Nb3Sn. However, there are currently no standard techniques usedto reduce Nb3Sn surface roughness. Since Nb3Sn is only 2-3 microns thick,it is difficult to selectively polish Nb3Sn without removing the entire layer.Here, we investigate reducing the surface roughness of Nb3Sn through ap-plying chemical polishing treatments, including modified versions of stan-dard techniques such as BCP and EP, among others. Through data ac-quired from AFM scans, we show the effects of these chemical treatments


01Ju

l–M

on

in reducing surface roughness and consider the changes in the chemicalcomposition of Nb3Sn that may occur through the etching process.

MOP014 Electroplating of Sn Film on Nb Substrate for Generating Nb-Sn ThinFilms and Post Laser AnnealingZ. Sun, M. Liepe, R.D. Porter (Cornell University (CLASSE)) T. Arias,A.B. Connolly, J.M. Scholtz, N. Sitaraman, M.O. Thompson (Cornell Univer-sity) X. Deng (University of Virginia) K.D. Dobson (University of Delaware)Nb3Sn thin film is an important candidate for next-generation supercon-ducting radio frequency (SRF) cavities. However, the RF performance ofcurrent Nb3Sn cavities is greatly affected by grain boundaries and surfaceroughness. Here, we propose and demonstrate a laser annealing tech-nique to enable the epitaxial growth of Nb3Sn grains and also reduce thefilm surface roughness. Preliminary results show that the Nb3Sn surfaceabsorbs 45% of the laser light at a wavelength of 308 nm. Thus, we use aXeCl excimer laser (308 nm) to melt the film surface, and the solidificationprocess provides epitaxy from the underlying Nb substrate. Multiple laserscanning is investigated to achieve the desired film thickness. The epitax-ial growth of Nb3Sn films is confirmed by cross-section scanning electronmicroscope (SEM), and the surface roughness after laser annealing is char-acterized using atomic force microscopy (AFM).

MOP015 RF Performance Sensitivity to Tuning of Nb3Sn Coated CEBAF CavitiesG.V. Eremeev, N.A. Huque, F. Marhauser (JLab) U. Pudasaini (The Collegeof William and Mary)Nb3Sn has the potential to surpass niobium as the material of choice forSRF applications. The potential of this material stems from a larger super-conducting energy gap, which leads to expectations of a higher RF criticalfield and a lower RF surface resistance. The appeal of better superconduct-ing properties is offset by the relative complexity of producing practicalNb3Sn structures, and Nb3Sn sensitivity to lattice disorder challenges theuse of the material for practical applications. Such sensitivity is indirectlyprobed during SRF cavity development, when the cavity is tuned to matchthe desired accelerator frequency. In the course of recent experiments wehave coated and tuned several multi-cell cavities. Cold RF measurementsbefore and after tuning showed degradation in cavity performance aftertuning. The results of RF measurement were compared against strain evo-lution on Nb3Sn surface during tuning based on CST and ANSYS models.

MOP016 Insights Into Nb3Sn Coating of CEBAF Cavities From Witness SampleAnalysisG.V. Eremeev, M.J. Kelley, C.E. Reece (JLab) M.J. Kelley, U. Pudasaini (TheCollege of William and Mary)With the progress made in the Nb3Sn coatings on single-cell SRF cavities,development is ongoing to reproduce single-cell cavity results on practi-cal structures such as CEBAF 5-cell cavities. During CEBAF cavity coatingdevelopment, several changes from the single-cell procedure to the coat-ing setup and the heating profile were introduced to improve the qualityof Nb3Sn films. To witness the properties of grown Nb3Sn films in differ-ent cavity locations, 10 mm x 10 mm samples were positioned in strategic


01Ju

l–M

on

places within the coating chamber. Composition and structure of the sam-ples were analyzed with surface analytic techniques and correlated withsample location during coatings. Implications from sample analysis toNb3Sn coatings on different geometries are discussed in this contribution.

MOP017 Analysis of Magnetic Vortex Dissipation in Sn Segregated Grain Bound-aries in Nb3Sn CavitiesA.R. Pack, J.M. Carlson, M.K. Transtrum (Brigham Young University)T. Arias, D. Liarte, A. Senanian, J.P. Sethna, N. Sitaraman (Cornell Univer-sity) J. Lee, S. Posen (Fermilab)We study mechanisms of vortex nucleation in Nb3Sn SRF cavities usinga combination of experimental, theoretical, and computational methods.TEM and TEM-EDS images of some Nb3Sn cavities show Sn segregation ingrain boundaries with widths ∼3 nm in chemical composition and ∼1nmin structural variation. The excess Sn forms as anti-site defects in the A15Nb3Sn lattice. We use time-dependent Ginzburg-Landau theory to under-stand the role of the observed segregation on magnetic vortex nucleation.We model the Sn segregation as a lowering of the local critical temperature.Our simulations indicate that material variations on this scale will nucle-ate vortices in the grain boundary. Depending on the magnitude of the ap-plied field, vortices may remain pinned in the grain boundary or penetratethe grain itself. We estimate the superconducting losses due to vorticesfilling grain boundaries and compare with observed performance degra-dation with higher magnetic fields. We additionally estimate the volumethat would need to be filled with vortices to match experimental observa-tions of cavity heating.

MOP018 Recent Results From Nb3Sn Single Cell Cavities Coated at Jefferson LabU. Pudasaini, M.J. Kelley (The College of William and Mary) G. Ciovati,G.V. Eremeev, M.J. Kelley, C.E. Reece (JLab) M.J. Kelley, J. Tuggle (VirginiaPolytechnic Institute and State University)Because of superior superconducting properties (Tc ∼18.3 K, Hsh∼425 mT and ∆ ∼3.1 meV), Nb3Sn promises better SRF performance (Qand Eacc) and higher operating temperature (4.2 K vs. 2 K) than niobium.Several single cell cavities along with witness samples were recently coatedwith Nb3Sn following an upgrade of the coating system. Despite the pres-ence of Q-slope in several cavity coatings, the Q-slope field dependencediffered from the previously observed “Wuppertal” Q-slope. RF testing ofcavities and sample surface studies were used to refine the coating proto-col. Under the best conditions yet tested, we measured a Nb3Sn cavity withquality factor above 2×1010 at Eacc ∼15 MV/m at 4 K, without a strong Q-slope. We will discuss recent results from Nb3Sn-coated single-cell cavitieslinked with material studies of witness samples, coating process modifica-tions, and the possible mitigation of “Wuppertal” slope.

MOP019 Investigation of the Influence of Surface Preparation Methods on thePerformance of Superconducting CH-CavitiesP. Müller, M. Basten, M. Busch, T. Conrad, H. Podlech (IAP) K. Aulenbacher,F.D. Dziuba, M. Miski-Oglu (HIM) W.A. Barth (GSI)The Institute of Applied Physics (IAP) introduced the superconducting


01Ju

l–M

on

multi-gap CH-structure, which is mainly designed for low beta hadron ac-celeration. In 2017, a 217 MHz sc CH-structure was successfully testedwith beam at GSI and multiple CH-structures are currently under devel-opment for the GSI cw linac. RF performance of all sc cavities are lim-ited by the surface properties of the used material. Therefore, sufficientsurface preparation and optimization is necessary to achieve optimal per-formance. Presently as standard procedure BCP and HPR is used for CH-cavities. Several surface treatments will be applied to the very first CH-prototype, a 360 MHz, 19-cell cavity. Prior to the first treatment, the statusof the cavity was examined, including leak tests and performance tests at4 and 2 K. This paper presents the performance development of a sc CHcavity depending on different preparation methods.

MOP020 Development of New Chemical Polishing Acid to Resolve High Field Q-slopeD. Luo, E.S. Metzgar, L. Popielarski, K. Saito, S.M. Shanab, G.V. Simpson(FRIB) T. Nakajima, I. Nasu, Y. Okii, J. Taguchi (Nomura Plating Co, Ltd.)In our detail studies of high field Q-slope we have concluded that nitrogencontamination from the nitric acid is the main cause of the degradation ofthe Q in buffered chemical polished cavities. According to this result, wehave started developing new nitrogen-free chemical polishing acid. We re-place HNO3 with H2O2 as the new oxidizer. In this paper, some Nb couponsample results with new acid will be reported, as our first step, developingthe new acid that the resulting surface roughness no worse than conven-tional BCP, is completed.

MOP021 Surface Characterization of Nitrogen Doped SRF Grade NiobiumCoupons and Cavities With Buffer Chemical Polishing and Electropol-ishingP. Dhakal, G. Ciovati (JLab) S. Balachandran, P.J. Lee (NHMFL) S. Chetri(ASC)Recent advances in the processing of bulk superconducting radio fre-quency (SRF) niobium cavities via interior surface impurity diffusion haveresulted in significant improvements in their quality factor (Q0). The mo-tivation for the development of these processes is to reduce the cryogenicoperating cost of current and future accelerators. In particular, nitrogen-doping consists of annealing of a niobium cavity at 800oC in the pres-ence of a partial pressure of nitrogen of ∼25 mTorr, which diffuses intothe Nb surface and NbN precipitates are also produced on the surfacewhich must be subsequently removed by electropolishing. However, theexact mechanism of the nitrogen diffusion and its role on improvementon quality factor is not fully understood. In this contribution, we presentthe systematic characterization of nitrogen doped niobium via scanningelectron microscopy, x-ray photoelectron spectroscopy and secondary ionmass spectroscopy in order to understand the role of nitrogen doping onthe performance of SRF cavities. Furthermore, we present the rf mea-surements on single cell cavities made from fine grain and large grain Nbtreated with nitrogen doping followed by BCP.


01Ju

l–M

on

MOP022 Superconducting RF Cavity Materials Research at the S-DALINACR. Grewe, L. Alff, M. Arnold, J. Conrad, S. Flege, M. Major, N. Pietralla (TUDarmstadt) F. Hug (IKP)Current state-of-the-art superconducting rf (srf) accelerators are mostlyusing cavities made of high RRR bulk niobium (Nb). The maximum fieldgradients and quality factors (Q0) of these cavities are basically reachednow. To further increase the srf cavity properties for future accelerator fa-cilities, research of new materials for srf cavity applications is necessary.The current research at the S-DALINAC is focused on the developmentof bake-out procedures of Nb samples and cavities in nitrogen (N) atmo-sphere of up to 100 mbar to nucleate the delta-phase (d-phase) of the Nb-N binary system. The d-phase has superconducting properties which ex-ceed the properties of bulk Nb. This makes the d-phase attractive for srfapplications. The vertical test cryostat (vt) at the S-DALINAC has been up-graded and recommissioned to allow investigations of the quality factorand accelerating field gradients of cavities before and after bake-out. Thevt upgrade includes a newly developed variable input coupling to allowmatching of the external q-factor (Qex) to Q0. The results of the ongoingresearch of the nitrogen atmosphere bake-out procedures and the upgradeof the vt will be presented.

MOP023 Nitrogen Infusion Sample R&D at DesyC. Bate, A. Dangwal Pandey, B. Foster, T.F. Keller, D. Reschke, J. Schaffran,S. Sievers, H. Weise, M. Wenskat (DESY) A. Stierle (University of Hamburg)The European XFEL continuous wave upgrade requires cavities with re-duced surface resistance (high Q-values) for high duty cycle while main-taining high accelerating gradient for short-pulse operation. A possibleway to meet the requirements is the so-called nitrogen infusion proce-dure. However, a fundamental understanding and a theoretical model ofthis method are still missing. The approach shown here is based on sampleR&D, with the goal to identify all key parameters of the process and estab-lish a stable, reproducible recipe. To understand the underlying processesof the surface evolution, which gives improved cavity performance, ad-vanced surface analysis techniques (e.g. SEM/EDX, TEM, XPS, TOF-SIMS)are utilized. Additionally, a small furnace just for samples was set up tochange and explore the parameter space of the infusion recipe. Resultsof these analyses, their implications for the cavity R&D and next steps arepresented.

MOP024 Vacancy-Hydrogen Dynamics in Samples During Low Temperature Bak-ingM. Wenskat, C. Bate, D. Reschke (DESY) C. Bate (University of Hamburg)M. Butterling, E. Hirschmann, M.O. Liedke, A. Wagner (HZDR) J. Cizek(Charles University)The recent discovery of a modified low temperature baking process lead toa reduction of surface losses and an increase of the accelerating gradient ofTESLA shape cavities. The hypothesis linking the accelerator performanceand the treatment is the suppression of lossy nanohydrides via defect trap-ping, with vacancy-hydrogen complexes forming at the lower tempera-


01Ju

l–M

on

tures. Utilizing Doppler broadening Positron Annihilation Spectroscopyand Positron Annihilation Lifetime Spectroscopy samples made from Eu-ropean XFEL niobium sheets and cavity cut-outs were investigated. Theevolution of vacancies, hydrogen and their interaction at different temper-ature levels have been studied during in-situ annealing. Measurements ofniobium samples and a correlation between RF, material properties, andV-H distribution in cavity cut-outs has been done.

MOP025 Cavity Cut-out Studies of a 1.3 GHz Single-cell Cavity After a Failed Ni-trogen Infusion ProcessM. Wenskat, C. Bate, T.F. Keller, D. Reschke (DESY) C. Bate (University ofHamburg) A. Jeromin (DESY Nanolab, FS-NL) F. Kramer, J.M. Köszegi (HZB)R&D on the nitrogen infusion process at DESY produced at the beginninga series of 1.3 GHz single-cell cavities which have shown severe deteriora-tion in the vertical cold test which was completely unexpected and couldnot be explained. To investigate the reason for the deterioration, one ofthose cavities was optically inspected and a T- and H-Map test was donein collaboration with HZB. Together with 2nd Sound data, regions of inter-ests were identified and cut from the cavity. Subsequent surface analysistechniques (SEM/EDX, SIMS, PIXE, EBSD, DB-PAS, PALS, XPS) were ap-plied in order to identify the reason for the deterioration. Especially thedifferences between hot and cold spots as well as quench spots identifiedby T-Mapping were investigated.

MOP026 A Cross-Lab Qualification of Modified 120oC Baked CavitiesM. Wenskat, D. Reschke, J. Schaffran, L. Steder, M. Wiencek (DESY)D. Bafia, A. Grassellino, O.S. Melnychuk (Fermilab) A.D. Palczewski (JLab)M. Wiencek (IFJ-PAN)Within a global effort to understand and standardize the nitrogen-infusionand the low T bake procedure, one large grain and two fine grain single-cellcavity were treated and tested at FNAL and then send to other labs includ-ing DESY and JLab for further studies.

MOP027 Study on Nitrogen-Infusion Using KEK New FurnaceK. Umemori, E. Kako, T. Konomi, S. Michizono, H. Sakai (KEK) T. Okada(Sokendai) J. Tamura (JAEA/J-PARC)KEK has been carried out high-Q/high-G R&D, to realize high performanceof SRF cavities toward ILC. KEK constructed a new furnace, which is ded-icated for N-infusion studies. We performed more than 10 times of N-infusion trials using 1.3 GHz single-cell cavities. Some results showed bet-ter Q-values up to high field, however, some results showed degraded Q-Eslopes probably due to contamination. Improvement of accelerating gra-dient is not observed at moment. We have tried to clean the furnace andNitrogen injection line to reduce the effect of contamination. Details ofprocedures of N-infusion, results of vertical tests, condition of the furnaceincluding RGA spectrum and Nb sample analysis results are shown.


01Ju

l–M

on

MOP028 Materials Science Investigations of Nitrogen-Doped Niobium for SRFCavitiesM. Major, L. Alff, M. Arnold, J. Conrad, S. Flege, R. Grewe, N. Pietralla (TUDarmstadt)Niobium is the standard material for superconducting RF (SRF) cavitiesfor particle acceleration. Superconducting materials with higher criti-cal temperature or higher critical magnetic field allow cavities to work athigher operating temperatures or higher accelerating fields, respectively.Enhancing the surface properties of the superconducting material in therange of the penetration depth is also beneficial. One direction of searchfor new materials with better properties is the modification of bulk nio-bium by nitrogen doping. In the Nb-N phase diagram, the cubic delta-phase of NbN has the highest critical temperature. Niobium sampleswere annealed and N-doped in the high-temperature furnace at TU Darm-stadt and investigated at its Materials Research Department with respectto structural modifications. Secondary ion mass spectrometry showed atwhich conditions N-diffusion takes place. X-ray diffraction (XRD) con-firmed the appearance of NbN and Nb2N phases for the optimized dopingprocess. XRD pole figures also showed grain growth during sample anneal-ing.

MOP029 N-Doping Studies With Single-Cell Cavities for the SHINE ProjectJ.F. Chen, H.T. Hou, Y.F. Liu, D. Wang, L. Yin (SARI-CAS) Y.W. Huang (Shang-hai Tech University) Z. Wang (SINAP)The SHINE SRF accelerator is designed to operate in CW mode with morethan six hundred SC cavities. High-Q cavities are necessary to reduce thecost of construction and operation of the cryogenic system. N-doping andLarge-grain cavities have been considered as the two possible options. Inthis paper, we present N-doping studies with both 1.3 GHz and 3.9 GHzsingle-cell cavities for the SHINE project.

MOP030 Analysis of Surface Nitrides Created During “Doping” Heat Treatmentsof NiobiumJ.K. Spradlin, A.D. Palczewski, C.E. Reece, H. Tian (JLab)The benefits of reduced RF losses from interstitial “doping” of niobium arewell established. Many of the details involved in the process remain yet tobe elucidated. The niobium surface reacted with low-pressure nitrogen at800oC presents a surface with chemical reactivity different than standardniobium. While standard “recipes” are being used to produce cavities, weseek additional insight into the chemical processes that may be used toremove the “undesirable” as-formed surface layer. This may lead to newprocessing routes or quality assurance methods to build confidence thatall surface “nitrides” have been removed. We report a series of alternatechemistry treatments and subsequent morphological examinations andinterpret the results. We also introduce a new standardized Nb sample sys-tem in use for efficient characterization of varying doping protocols andcross-laboratory calibration.


01Ju

l–M

on

MOP031 Investigation of Frequency Behavior Near Tc of Niobium Superconduct-ing Radio-Frequency CavitiesD. Bafia, J. Zasadzinski (IIT) M. Checchin, A. Grassellino, O.S. Melnychuk,A.S. Romanenko, D.A. Sergatskov (Fermilab)This poster will present a systematic investigation of the resonant fre-quency behavior of niobium SRF cavities subject to different surface pro-cessing (nitrogen doping, nitrogen infusion, 120oC bake, EP, etc.) near thecritical transition temperature. We find features occurring in frequencyversus temperature (FvsT) data near Tc that seem to vary with surface pro-cessing. Emphasis is placed on one of the observed features: a dip in thesuperconducting resonant frequency below the normal conducting valuewhich is prominent in nitrogen doped cavities and appears to be a signa-ture of nitrogen doping. This gives further insights on the mechanismsresponsible for the large increase in performance of cavities subject to thissurface treatment. The magnitude of this dip in frequency is studied andrelated to possible physical parameters such as the concentration of impu-rities near the surface and the design resonant frequency of the cavity. Apossible explanation for the meaning of this dip is discussed, namely, thatit is a result of strong coupling between electrons and phonons within theresonator.

MOP032 Effect of Low Temperature Infusion Heat Treatments on Superconduct-ing Cavity PerformanceP.N. Koufalis, M. Ge, M. Liepe, J.T. Maniscalco, Z. Sun (Cornell University(CLASSE))Under specific circumstances, low temperature infusion heat treatmentsof niobium cavities have resulted in the ubiquitous ‘Q-rise’. This is anincrease in quality factor with increasing field strength or equivalently adecrease in the temperature-dependent component of the surface resis-tance. We investigate the results of various infusion conditions with infu-sion bake time and temperature as a free parameters. To study the verynear surface effects of infusion, we employ HF rinsing and oxypolishing toremove several or tens of nm at a time. We present results from RF per-formance tests of low temperature infusion heat treated niobium cavities,and correlate these with SIMS impurity depth profiles obtained from wit-ness samples.

MOP033 The Beam Dynamics Updates of the Fermilab PIP-II 800 MeV Supercon-ducting LinacA. Saini, V.P. Yakovlev (Fermilab) E. Pozdeyev (FRIB)The Proton Improvement Plan (PIP) -II is a high intensity proton facilitybeing developed to support a neutrino program over the next two decadesat Fermilab. At its core is the design and construction of a ContinuousWave compatible superconducting radio frequency linear accelerator thatwould accelerate an average beam current of 2 mA up to 800 MeV. This pa-per presents recent updates in the beam dynamics leading to a reliable androbust linac design and simplifying the cryo-module assembly.


01Ju

l–M

on

MOP034 European XFEL: Accelerating Module Repair at DESYD. Kostin, J. Eschke, K. Jensch, N. Krupka, D. Reschke, S. Saegebarth,J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, S. Sievers, N. Steinhau-Kühl, E. Vogel, H. Weise, M. Wiencek, B. van der Horst (DESY)European XFEL is in operation since 2017. The project energy of 17.5 GeVwas reached, even with last 4 main linac accelerating modules not yet in-stalled. 2 of 4 not installed modules did suffer from a strong cavities per-formance degradation, namely increased field emission, and must be re-paired. First of two modules is reassembled and tested. The module testresults confirm a successful repair action. The module repair and test stepsare described together with cavities performance evolution.

MOP035 Cryogenic Infrastructure at BESSY II – Current Installations and FutureDevelopmentsS. Heling, W. Anders, J. Heinrich, A. Hellwig, K. Janke, S. Rotterdam (HZB)In Berlin-Adlershof the Helmholtz-Zentrum Berlin (HZB) is operating thesynchrotron radiation source BESSY II. Two superconducting wave-lengthshifter magnets are built-in the storage ring of BESSY II which are cooledwith liquid helium. Additionally several test facilities for superconductingcavities are operated at HZB needing helium at 1.8 K. The required heliumis supplied by two helium liquefiers. Parallel to operation of the existingfacilities the BERL inPro project will qualify as test facility for ERL scienceand technology. In order to guarantee the required supply with helium atdifferent temperature levels one of the existing helium liquefiers has beenrelocated to the new accelerator building and the existing cryogenic infras-tructure has been upgraded with a new 10 000 L dewar, three valve boxes, acold compressor box, warm pumps and a 80 K helium system. This paperspecifies the setup of the above described helium cryoplants in detail andgives insight into the challenges of operation. The paper concludes withan outlook of the upcoming developments of the cryogenic infrastructureat HZB.

MOP036 Microphonics Suppression Study in ARIEL e-Linac CryomodulesY. Ma, R.E. Laxdal, S. Liu, X. Wang (TRIUMF)Now the stage of the 30 MeV portion of ARIEL (The Advanced Rare Iso-tope Laboratory) e-Linac (1.3 GHz, SRF) is under commissioning which in-cludes an injector cryomodule (ICM) with a single nine-cell cavity and the1st accelera

Date post:	23-Oct-2020
Category:	Documents
Upload:	others
View:	3 times
Download:	0 times

INT SRF19 CGDINA5 20s - SRF2019 · Peter Michel, HZDR, IPC Chair Claire Antoine, CEA Saclay Olivier...

Documents