Author: Araki, H.
Paper Title Page
MOPMB033 Efforts to Suppress Field Emission in SRF Cavities at KEK 167
 
  • M. Omet, H. Araki, T. Dohmae, H. Ito, R. Katayama, K. Umemori, Y. Yamamoto
    KEK, Ibaraki, Japan
  
  Our main ob­jec­tive is to achieve as high as pos­si­ble qual­ity fac­tors Q₀ and max­i­mal ac­cel­er­at­ing volt­ages Eacc within 1.3 GHz su­per­con­duct­ing radio fre­quency (SRF) cav­i­ties. Be­side an ad­e­quate sur­face treat­ment, key to achieve good per­for­mance is a proper as­sem­bly in the clean room prior cav­ity test­ing or op­er­a­tion. In this con­tri­bu­tion we pre­sent the meth­ods and re­sults of our ef­forts to get a bet­ter un­der­stand­ing of our clean room en­vi­ron­ment and the par­tic­u­late gen­er­a­tion caused dur­ing the as­sem­bly work. Fur­ther­more, we pre­sent the mea­sures taken to sup­press filed emis­sion, fol­lowed by an analy­sis of ver­ti­cal test re­sults of the last six years.  
poster icon Poster MOPMB033 [1.532 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB033  
About • Received ※ 14 June 2023 — Revised ※ 25 June 2023 — Accepted ※ 02 September 2023 — Issue date ※ 02 September 2023
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TUIXA03
 Surface Resistance and Trapped Flux Sensitivity as Function of Baking Temperature  
 
  • H. Ito, H. Araki, K. Umemori
    KEK, Ibaraki, Japan
  
  We have in­ves­ti­gated the in­flu­ence of fur­nace bak­ing at var­i­ous bak­ing tem­per­a­tures on Q-value and trapped flux sen­si­tiv­ity. We find that mid-tem­per­a­ture bak­ing is a promis­ing process for ob­tain­ing a high Q-value, but it re­sults in a high flux sen­si­tiv­ity. In par­tic­u­lar, 300°C bak­ing re­sults in ex­tremely high Q-value and sen­si­tiv­ity. In­stead, 250°C bak­ing is found to be a more ef­fec­tive process than 300°C bak­ing for ac­cel­er­a­tor ap­pli­ca­tions, as it can reach a higher ac­cel­er­at­ing gra­di­ent while keep­ing a high Q-value and a lower sen­si­tiv­ity. In ad­di­tion, we find that 200°C bak­ing can reach a higher Q-value at a high ac­cel­er­at­ing gra­di­ent e.g. 35 MV/m com­pared to 120°C 48 h bak­ing that is ap­plied to the cav­ity nor­mally.  
slides icon Slides TUIXA03 [32.219 MB]  
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WEIXA04 Development of the Directly-Sliced Niobium Material for High Performance SRF Cavities 634
 
  • A. Kumar, H. Araki, T. Dohmae, H. Ito, T. Saeki, K. Umemori, A. Yamamoto, M. Yamanaka
    KEK, Ibaraki, Japan
  • A. Yamamoto
    CERN, Meyrin, Switzerland
  
  For the pur­pose of cost re­duc­tion for the ILC, KEK has been con­duct­ing R&D on di­rect sliced Nb ma­te­ri­als such as large grain and medium grain Nb. Sin­gle-cell, 3-cell, and 9-cell cav­i­ties have been man­u­fac­tured, and each has demon­strated a high-per­for­mance ac­cel­er­at­ing gra­di­ent ex­ceed­ing 35 MV/m. The re­sults of ap­ply­ing high-Q/high-G recipes, such as two-step bak­ing and fur­nace bak­ing to these cav­i­ties are also shown. More­over, me­chan­i­cal tests have been car­ried out for the be­fore­men­tioned ma­te­ri­als to eval­u­ate their strength for ap­pli­ca­tion to the High-Pres­sure Gas Safety Law. The sta­tus of de­vel­op­ment of these large grain and Medium grain Nb will be pre­sented.  
slides icon Slides WEIXA04 [3.773 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA04  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 12 July 2023
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