Keyword: niobium
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MOPAB376 Design and Fabrication of a Quadrupole Resonator for SRF R&D SRF, cavity, quadrupole, radio-frequency 1158
 
  • R. Monroy-Villa, W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Gorgi Zadeh, P. Putek
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • R. Monroy-Villa, D. Reschke, J.H. Thie
    DESY, Hamburg, Germany
  
  As Nb su­per­con­duct­ing ra­dio-fre­quency (SRF) cav­i­ties are now ap­proach­ing the the­o­ret­i­cal lim­its of the ma­te­r­ial, a va­ri­ety of dif­fer­ent sur­face treat­ments have been de­vel­oped to fur­ther im­prove their per­for­mance; al­though no fully un­der­stood the­ory is yet avail­able. Small su­per­con­duct­ing sam­ples are stud­ied to char­ac­ter­ize their ma­te­r­ial prop­er­ties and their evo­lu­tion under dif­fer­ent sur­face treat­ments. To study the RF prop­er­ties of such sam­ples under re­al­is­tic SRF con­di­tions at low tem­per­a­tures, a test cav­ity called quadru­pole res­onator (QPR) is cur­rently being fab­ri­cated. In this work we re­port the sta­tus of the QPR at Uni­ver­sität Ham­burg in col­lab­o­ra­tion with DESY. Our de­vice is based on the QPRs op­er­ated at CERN and at HZB and its de­sign will allow for test­ing sam­ples under cav­ity-like con­di­tions, i.e., at tem­per­a­tures be­tween 2K and 8 K, under mag­netic fields up to 120mT and with op­er­at­ing fre­quen­cies of 433 MHz, 866 MHz and 1300 MHz. Fab­ri­ca­tion tol­er­ance stud­ies on the elec­tro­mag­netic field dis­tri­b­u­tions and sim­u­la­tions of the sta­tic de­tun­ing of the de­vice, to­gether with a sta­tus re­port on the cur­rent man­u­fac­tur­ing process, will be pre­sented.  
poster icon Poster MOPAB376 [1.119 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB376  
About • paper received ※ 26 May 2021       paper accepted ※ 09 June 2021       issue date ※ 17 August 2021  
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MOPAB379 Topological Optimization on SRF Cavities for Nuclear and High Energy Physics cavity, superconducting-cavity, radiation, simulation 1162
 
  • H. Gassot
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  Topol­ogy op­ti­miza­tion has been de­vel­oped for more than twenty years. The progress of ad­di­tive man­u­fac­tur­ing boosts the de­vel­op­ment in topo­log­i­cal op­ti­miza­tion since the de­sign can be com­pletely in­no­vated and re­al­ized by 3D print­ing. The po­ten­tial for cost re­duc­tions thanks to weight min­i­miza­tion give an in­ter­est­ing per­spec­tive for the small pro­duc­tion of nio­bium su­per­con­duct­ing ra­dio-fre­quency cav­i­ties, com­monly used in ac­cel­er­a­tors. The tra­di­tional man­u­fac­tur­ing tech­nolo­gies of cav­i­ties are based on multi-stage processes while ad­di­tive man­u­fac­tur­ing tech­nolo­gies can built fully func­tional parts in a sin­gle op­er­a­tion. For mod­ern ac­cel­er­a­tors that use su­per­con­duct­ing linac, in­clud­ing en­ergy re­cov­ery linacs (ERLs), it is par­tic­u­larly im­por­tant to know the per­spec­tives of ad­di­tive man­u­fac­tur­ing for SRF cav­i­ties. In this paper, we try to build a pre­lim­i­nary per­cep­tion of topo­log­i­cal op­ti­miza­tion in su­per­con­duct­ing cav­i­ties man­u­fac­tur­ing in­no­va­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB379  
About • paper received ※ 11 May 2021       paper accepted ※ 17 August 2021       issue date ※ 15 August 2021  
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MOPAB383 Pressure Test for Large Grain and Fine Grain Niobium Cavities cavity, SRF, experiment, FEM 1173
 
  • M. Yamanaka, T. Dohmae, H. Inoue, T. Saeki, K. Umemori, Y. Watanabe, K. Yoshida
    KEK, Ibaraki, Japan
  • K. Enami
    Tsukuba University, Ibaraki, Japan
  
  The pres­sure test was per­formed using a fine grain (FG) and a large grain (LG) nio­bium cav­i­ties. The cav­ity is 1.3 GHz 3-cell TESLA-like shape. The cav­ity was housed in a steel ves­sel. Water is sup­plied into the ves­sel and the cav­ity out­side is pres­sur­ized. The ap­ply­ing pres­sure and the nat­ural fre­quency of cav­ity were mea­sured dur­ing the pres­sure test. The FG and LG cav­i­ties were de­formed greatly and the pres­sure dropped sud­denly at 3.4 MPa and 1.6 MPa, re­spec­tively. The fre­quency shifted up to 3.4 MHz and 1.3 MHz, re­spec­tively. There was no leak after the pres­sure test, so the cav­ity did not rup­ture under above pres­sure. The re­sult of the pres­sure at LG cav­ity is less half than that of the FG cav­ity. We cal­cu­lated the stress dis­tri­b­u­tion in the struc­ture by ap­ply­ing outer water pres­sure using a FEM. The max­i­mum stress at cell when above test pres­sure is ap­plied, are 146 MPa in FG and 73 MPa in LG, re­spec­tively. These stresses are sim­i­lar to ten­sile strength of nio­bium spec­i­men mea­sure by our­selves. The re­sult of pres­sure tests agrees well with the cal­cu­la­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB383  
About • paper received ※ 19 May 2021       paper accepted ※ 22 June 2021       issue date ※ 28 August 2021  
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MOPAB384 Nb3Sn Coating of Twin Axis Cavity for Accelerator Applications cavity, linac, SRF, dipole 1175
 
  • J.K. Tiskumara, S.U. De Silva, J.R. Delayen, H. Park
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, H. Park, U. Pudasaini, C.E. Reece
    JLab, Newport News, Virginia, USA
  • G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  
  Funding: Research supported by DOE Office of Science Accelerator Stewardship Program Award DE- SC0019399. Partially authored by Jefferson Science Associates under contract no. DEAC0506OR23177
A Su­per­con­duct­ing twin axis cav­ity con­sist­ing of two iden­ti­cal beam pipes that can ac­cel­er­ate and de­cel­er­ate beams within the same struc­ture has been pro­posed for the En­ergy Re­cov­ery Linac (ERL) ap­pli­ca­tions. There are two nio­bium twin axis cav­i­ties at JLab fab­ri­cated with the in­ten­tion of later Nb3Sn coat­ing and now we are pro­gress­ing to coat them using vapor dif­fu­sion method. Nb3Sn is a po­ten­tial al­ter­nate ma­te­r­ial for re­plac­ing Nb in SRF cav­i­ties for bet­ter per­for­mance and re­duc­ing op­er­a­tional costs. Be­cause of ad­vanced geom­e­try, larger sur­face area, in­creased num­ber of ports and hard to reach areas of the twin axis cav­i­ties, the usual coat­ing ap­proach de­vel­oped for typ­i­cal el­lip­ti­cal sin­gle-axis cav­i­ties must be eval­u­ated and re­quires to be ad­justed. In this con­tri­bu­tion, we re­port the first re­sults from the coat­ing of a twin axis cav­ity and dis­cuss cur­rent chal­lenges with an out­look for the fu­ture. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB384  
About • paper received ※ 19 May 2021       paper accepted ※ 24 May 2021       issue date ※ 27 August 2021  
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MOPAB386 Development of Nitrogen-Doping Technology for SHINE cavity, SRF, ECR, linac 1182
 
  • Y. Zong, X. Huang, Z. Wang
    SINAP, Shanghai, People’s Republic of China
  • J.F. Chen, H.T. Hou, D. Wang, J.N. Wu, Y.X. Zhang
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • P.C. Dong
    Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
  • Y.W. Huang
    ShanghaiTech University, Shanghai, People’s Republic of China
  • J. Rong
    SSRF, Shanghai, People’s Republic of China
  
  The Shang­hai HIgh rep­e­ti­tion rate XFEL aNd Ex­treme light fa­cil­ity (SHINE) is under con­struc­tion, which needs six hun­dred 1.3GHz cav­i­ties with high qual­ity fac­tor. In this paper, we pre­sent the newest stud­ies on sin­gle cell cav­i­ties with ni­tro­gen dop­ing and cold EP treat­ment, show­ing an ob­vi­ous im­prove­ment com­pared with the pre­vi­ous re­sults.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB386  
About • paper received ※ 21 May 2021       paper accepted ※ 08 June 2021       issue date ※ 20 August 2021  
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MOPAB401 In-Situ EXAFS Investigations of Nb-Treatments in N2, O2 and N2-O2 Mixtures at Elevated Temperatures vacuum, site, experiment, cavity 1214
 
  • P. Rothweiler, B. Bornmann, J. Klaes, D. Lützenkirchen-Hecht, R. Wagner
    University of Wuppertal, Wuppertal, Germany
  
  Funding: We gratefully acknowledge financial support by the German Federal Ministry of Education and Research (BMBF) under project No. 05H18PXRB1.
Smooth poly­crys­talline Nb metal foils were treated in di­lute gas at­mos­pheres using a tem­per­a­ture of 900 °C. Trans­mis­sion mode X-ray ab­sorp­tion spec­troscopy (EX-AFS) at the Nb K-edge was used to in­ves­ti­gate changes in the atomic short-range order struc­ture of the bulk Nb-ma­te­r­ial in-situ. The ex­per­i­ments were per­formed in a ded­i­cated high-vac­uum cell that al­lows treat­ments in a di­lute gas at­mos­phere and tem­per­a­tures of up to 1200 °C. Typ­i­cal treat­ments in­clude (i) pre-heat­ing at 900 °C under high-vac­uum, (ii) gas ex­po­sure at the de­sired pres­sure and tem­per­a­ture, and (iii) cooldown to room tem­per­a­ture under vac­uum. EXAFS data were col­lected dur­ing the en­tire pro­ce­dure with a time res­o­lu­tion of 1 s. For the treat­ments in N2 at T = 900°C, the data show sub­tle changes in the Nb-EX­AFS, that are com­pat­i­ble with N-dop­ing of the bulk Nb, and the re­sults sug­gest Nb up­take on oc­ta­he­dral in­ter­sti­tial sites. How­ever, even a small O2-par­tial pres­sure leads to dis­tinct ox­i­da­tion of the Nb. The re­sults will be dis­cussed in more de­tail in the pre­sen­ta­tion. 		 
poster icon Poster MOPAB401 [2.032 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB401  
About • paper received ※ 19 May 2021       paper accepted ※ 26 May 2021       issue date ※ 27 August 2021  
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TUPAB342 Preliminary Cryogenic Cold Test Results of the First 9-Cell LSF Shape Cavity cavity, SRF, multipactoring, laser 2296
 
  • R.L. Geng, W.A. Clemens, R.S. Williams
    JLab, Newport News, Virginia, USA
  • S.A. Belomestnykh
    Fermilab, Batavia, Illinois, USA
  • Y. Fuwa
    JAEA/J-PARC, Tokai-mura, Japan
  • H. Hayano
    KEK, Ibaraki, Japan
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • Z. Li
    SLAC, Menlo Park, California, USA
  • V.D. Shemelin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supplemental support by US-Japan Collaboration on HEP.
Fol­low­ing suc­cess­ful pro­to­typ­ing and test­ing of sin­gle- & 5-cell LSF shape cav­i­ties *, **, the first 9-cell LSF shape cav­ity LSF9-1 was suc­cess­fully con­structed using an in­no­v­a­tive process at JLab with the in-house fa­cil­i­ties. The cav­ity was then shipped to KEK for post-fab­ri­ca­tion me­chan­i­cal ad­just­ment and ILC TDR style treat­ment and sur­face pro­cess­ing. Cold test­ing was car­ried out at the JLab VTA fa­cil­ity, in­stru­mented with a suite of Kyoto in­stru­ments. Fa­vor­able val­ues for the bath pres­sure de­tun­ing sen­si­tiv­ity and Lorentz force de­tun­ing co­ef­fi­cient were ex­per­i­men­tally mea­sured, val­i­dat­ing the de­sign im­prove­ment in cell stiff­en­ers. Pass-band mea­sure­ments in­di­cate 4 out of 9 cells reach­ing gra­di­ent ca­pa­bil­ity of > 45 MV/m, in­clud­ing 2 cells reach­ing 51 MV/m. Cor­nell OST de­tec­tors iden­ti­fied the cell and lo­ca­tion re­spon­si­ble for the cur­rent hard quench limit. Mul­ti­pact­ing-like bar­ri­ers ob­served in end cells are in­ves­ti­gated both an­a­lyt­i­cally and nu­mer­i­cally. The cav­ity was shipped to FNAL and re­ceived a light EP at the joint ANL/FNAL fa­cil­ity for fur­ther cold test­ing at Jlab. Two new 9-cell LSF cav­i­ties are being con­structed in­clud­ing one made of large-grain nio­bium ma­te­r­ial.
* R. L. Geng et al.,WEPWI013, IPAC15.
** R. L. Geng et al., MOP064, SRF’19.
 		 
poster icon Poster TUPAB342 [1.600 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB342  
About • paper received ※ 09 May 2021       paper accepted ※ 14 June 2021       issue date ※ 20 August 2021  
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TUPAB344 Evaluation of Anisotropic Magnetoresistive (AMR) Sensors for a Magnetic Field Scanning System for SRF Cavities cavity, SRF, experiment, MMI 2304
 
  • I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, J.R. Delayen
    JLab, Newport News, Virginia, USA
  
  Funding: Work supported by NSF Grant 100614-010. G. C. is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
One of the sig­nif­i­cant causes of resid­ual losses in su­per­con­duct­ing ra­dio-fre­quency (SRF) cav­i­ties is trapped mag­netic flux. The flux trap­ping mech­a­nism de­pends on many fac­tors that in­clude cool-down con­di­tions, sur­face prepa­ra­tion tech­niques, and am­bi­ent mag­netic field ori­en­ta­tion. Suit­able di­ag­nos­tic tools are not yet avail­able to quan­ti­ta­tively cor­re­late such fac­tors’ ef­fect on the flux trap­ping mech­a­nism. A mag­netic field scan­ning sys­tem (MFSS) con­sist­ing of AMR sen­sors, flux­gate mag­ne­tome­ters, or Hall probes is re­cently com­mis­sioned to scan the local mag­netic field of trapped vor­tices around 1.3 GHz sin­gle-cell SRF cav­i­ties. In this con­tri­bu­tion, we will pre­sent re­sults from sen­si­tiv­ity cal­i­bra­tion and the first tests of AMR sen­sors in the MFSS. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB344  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 29 August 2021  
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TUPAB400 Manufacturing of Ceramic Vacuum Chambers for Sirius On-Axis Kicker vacuum, kicker, HOM, target 2457
 
  • R. Defavari, O.R. Bagnato, M.W.A. Feitosa, F.R. Francisco, D.Y. Kakizaki, R.L. Parise, R.D. Ribeiro
    LNLS, Campinas, Brazil
  
  Ce­ramic vac­uum cham­bers were pro­duced by LNLS for the Sir­ius kick­ers. Alu­mina tubes with an el­lip­ti­cal inner shape of 9.5 mm (V) x 29 mm (H) and 500 mm long were suc­cess­fully man­u­fac­tured by a Brazil­ian com­pany. Metal­lic F136 ti­ta­nium flanges were brazed to Nb in­serts using Ag-58.5Cu-31.5Pd wt% alloy, these in­serts were brazed to the ce­ramic using Ag-26.7Cu-4.5Ti wt% ac­tive filler metal. A ti­ta­nium film was coated in­side the cham­ber using argon plasma by RF Mag­netron Sput­ter­ing tech­nique. Sam­ples have been in­ves­ti­gated by Scan­ning Elec­tron Mi­croscopy (SEM) to mea­sure film thick­ness along the inner sec­tion of the tube, coat­ing mor­phol­ogy, chem­i­cal com­po­si­tion and ho­mo­gene­ity. The total elec­tri­cal re­sis­tance of the tube was also mon­i­tored dur­ing the sput­ter­ing process to achieve the de­sired value (0.2 ohms/square). In this con­tri­bu­tion, we pre­sent the re­sults of an On-Axis kicker man­u­fac­tur­ing process de­vel­oped by LNLS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB400  
About • paper received ※ 18 May 2021       paper accepted ※ 31 May 2021       issue date ※ 29 August 2021  
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WEPAB381 Multipactor Simulations for MYRRHA Spoke Cavity: Comparison Between SPARK3D, MUSICC3D, CST PIC and Measurement multipactoring, electron, simulation, cavity 3606
 
  • N. Hu, M. Chabot, J.-L. Coacolo, D. Longuevergne, G. Olry
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • M.B. Belhaj
    ONERA, Toulouse, France
  
  The mul­ti­pactor ef­fect can lead to ther­mal break­down (quench), high field emis­sion and lim­ited ac­cel­er­at­ing gra­di­ent in su­per­con­duct­ing ac­cel­er­a­tor de­vices. To de­ter­mine the mul­ti­pactor break­down power level, mul­ti­pactor sim­u­la­tions can be per­formed. The ob­jec­tive of this study is to com­pare the re­sults given by dif­fer­ent sim­u­la­tion codes with the re­sults of ver­ti­cal test­ing of SRF cav­i­ties. In this paper, Spark3D, MU­S­IC­C3D and CST Stu­dio PIC solver have been used to sim­u­late the mul­ti­pactor ef­fect in Spoke cav­ity de­vel­oped within the frame­work of MYRRHA pro­ject. Then, a bench­mark of these three sim­u­la­tion codes has been made. The break­down power level, the mul­ti­pactor order and the most promi­nent lo­ca­tion of mul­ti­pactor are pre­sented. Fi­nally, the sim­u­la­tion re­sults are com­pared with the mea­sure­ments done dur­ing the ver­ti­cal tests.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB381  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 25 August 2021  
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THPAB320 ALD-Based NbTiN Studies for SIS R&D site, cavity, plasma, SRF 4420
 
  • I. González Díaz-Palacio, R.H. Blick, R. Zierold
    University of Hamburg, Hamburg, Germany
  • W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  Su­per­con­duc­tor-In­su­la­tor-Su­per­con­duc­tor mul­ti­lay­ers im­prove the per­for­mance of SRF cav­i­ties pro­vid­ing mag­netic screen­ing of the bulk cav­ity and lower sur­face re­sis­tance. In this frame­work NbTiN mix­tures stand as a po­ten­tial ma­te­r­ial of in­ter­est. Atomic layer de­po­si­tion (ALD) al­lows for uni­form coat­ing of com­plex geome­tries and en­ables tun­ing of the sto­i­chiom­e­try and pre­cise thick­ness con­trol in sub-nm range. In this talk, we re­port about NbTiN thin films de­posited by plasma-en­hanced ALD on in­su­lat­ing AlN buffer layer. The de­po­si­tion process has been op­ti­mized by study­ing the su­per­con­duct­ing elec­tri­cal prop­er­ties of the films. Post-de­po­si­tion ther­mal an­neal­ing stud­ies with vary­ing tem­per­a­tures, an­neal­ing times, and gas at­mos­pheres have been per­formed to fur­ther im­prove the thin film qual­ity and the su­per­con­duct­ing prop­er­ties. Our ex­per­i­men­tal stud­ies show an in­crease in Tc by 87.5% after ther­mal an­neal­ing and a max­i­mum Tc of 13.9 K has been achieved for NbTiN of 23 nm thick­ness. Fu­ture steps in­clude lat­tice char­ac­ter­i­za­tion, using XRR/XRD/EBSD/PALS, and SRF mea­sure­ments to ob­tain Hc1 and the su­per­con­duct­ing gap.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB320  
About • paper received ※ 24 May 2021       paper accepted ※ 23 July 2021       issue date ※ 18 August 2021  
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