Author: Goessel, A.    [Gössel, A.]
Paper Title Page
WEPWB065 Impact of Medium Temperature Heat Treatments on the Magnetic Flux Expulsion Behavior of SRF Cavities 731
SUSPB043   use link to see paper's listing under its alternate paper code  
 
  • J.C. Wolff, J. Eschke, A. Gössel, K. Kasprzak, D. Reschke, L. Steder, L. Trelle, M. Wiencek
    DESY, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program.
Medium tem­per­a­ture (mid-T) heat treat­ments at 300 °C are used to en­hance the in­trin­sic qual­ity fac­tor of su­per­con­duct­ing radio fre­quency (SRF) cav­i­ties. Un­for­tu­nately, such treat­ments po­ten­tially in­crease the sen­si­tiv­ity to trapped mag­netic flux and con­se­quently the sur­face re­sis­tance of the cav­ity. For this rea­son, it is cru­cial to max­i­mize the ex­pul­sion of mag­netic flux dur­ing the cool down. The flux ex­pul­sion be­hav­ior is next to the heat treat­ment mainly de­ter­mined by the geom­e­try, the nio­bium grain size and the grain ori­en­ta­tion. How­ever, it is also af­fected by pa­ra­me­ters of the cav­ity per­for­mance tests like the cool down ve­loc­ity, the spa­tial tem­per­a­ture gra­di­ent along the cav­ity sur­face and the mag­netic flux den­sity dur­ing the tran­si­tion of the crit­i­cal tem­per­a­ture. To im­prove the flux ex­pul­sion be­hav­ior and hence the ef­fi­ciency of fu­ture ac­cel­er­a­tor fa­cil­i­ties, the im­pact of these ad­justable pa­ra­me­ters as well as the mid-T heat treat­ment on 1.3 GHz TESLA-Type sin­gle-cell cav­i­ties is in­ves­ti­gated by a new ap­proach of a mag­ne­to­met­ric map­ping sys­tem. In this con­tri­bu­tion first per­for­mance test re­sults of cav­i­ties be­fore- and after mid-T heat treat­ment are pre­sented.
 
poster icon Poster WEPWB065 [3.077 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB065  
About • Received ※ 21 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 13 July 2023
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WEPWB092 Test-Stand for Conditioning of Fundamental Power Couplers at DESY 797
 
  • K. Kasprzak, Th. Buettner, A. Gössel, D. Klinke, D. Kostin, C. Müller, E. Vogel, M. Wiencek
    DESY, Hamburg, Germany
 
  Dur­ing the con­struc­tion of the Eu­ro­pean-XFEL, ac­tiv­i­ties re­lated to Fun­da­men­tal Power Cou­plers (FPCs) were out­sourced to ex­ter­nal part­ners and the for­mer FPC test-stand area at DESY was given up due to in­fra­struc­ture re­arrange­ments. For the study of var­i­ous XFEL up­grade sce­nar­ios a new test-stand for con­di­tion­ing of FPCs at DESY is re­quired. It will be used for eval­u­a­tion of new cou­pler prepa­ra­tion meth­ods with par­tic­u­lar em­pha­sis on Con­tin­u­ous Wave (CW) and long RF pulse op­er­a­tion. The new test-stand has been re­cently com­mis­sioned. Four FPCs have been pre­pared and tested. RF pulses were ap­plied to the cou­plers, start­ing with the short­est pos­si­ble pulse and in­creas­ing it’s power until max­i­mum power was reached. The process was re­peated with sev­eral pulse lengths until the max­i­mum RF pulse length was reached. A re­view of the com­mis­sion­ing and first op­er­a­tion ex­pe­ri­ence of the RF sys­tem are pre­sented here.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB092  
About • Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 16 July 2023
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THCAA02 Commissioning of the UHH Quadrupole Resonator at DESY 952
SUSPB045   use link to see paper's listing under its alternate paper code  
WEPWB074   use link to see paper's listing under its alternate paper code  
 
  • R. Monroy-Villa, W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • A. Gössel, D. Reschke, M. Röhling, M. Schmökel, J.H. Thie, M. Wiencek
    DESY, Hamburg, Germany
  • C. Martens
    University of Hamburg, Hamburg, Germany
 
  Funding: This work was supported by the BMBF under the research grants 05H18GURB1, 05K19GUB and 05H2021.
Push­ing the lim­its of the ac­cel­er­at­ing field or qual­ity fac­tor of SRF cav­i­ties be­yond pure Nb re­quires the im­ple­men­ta­tion of spe­cific inner sur­face treat­ments, which are yet to be stud­ied and op­ti­mized. One of the fun­da­men­tal chal­lenges in ex­plor­ing al­ter­na­tive ma­te­ri­als is that only sam­ples or cav­ity cuts can be fully char­ac­ter­ized from a ma­te­r­ial point of view. On the other hand, com­plete cav­i­ties allow for the SRF char­ac­ter­i­za­tion of the inner sur­face, while sam­ples can usu­ally only be an­a­lyzed using DC meth­ods. To ad­dress this prob­lem, a test res­onator for sam­ples, called "Quadru­pole Res­onator", was de­signed and op­er­ated at CERN and later at HZB. It al­lows for a full RF char­ac­ter­i­za­tion of sam­ples at fre­quen­cies of 0.42 GHz, 0.86 GHz, and 1.3 GHz, within a tem­per­a­ture range of 2-20 K and at mag­netic fields up to 120 mT. This work pre­sents the de­sign process, which in­cor­po­rated im­prove­ments mo­ti­vated by me­chan­i­cal and RF stud­ies and ex­pe­ri­ence, and the re­sults from both warm and cold com­mis­sion­ing are dis­cussed. More im­por­tant, the re­sults for the RF tests of a Nb sam­ple after un­der­go­ing a se­ries of heat treat­ments and an out­look of the fur­ther usage of the QPR is pre­sented.
 
slides icon Slides THCAA02 [6.677 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THCAA02  
About • Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 19 August 2023
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