Author: Dohmae, T.
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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TUPTB030 Development of Automatic Cleaning and Assembly Systems in Clean Room at KEK 463
 
  • Y. Yamamoto, T. Dohmae, M.H. Hiraki, H. Sakai, K. Umemori, T. Yamada
    KEK, Ibaraki, Japan
  
  At KEK, new clean work sys­tems in­clud­ing ver­ti­cal auto clean­ing sys­tem, re­place­ment sys­tem be­tween blank flange and bel­lows, and robot arm have been de­vel­oped and in­stalled since 2020 under the col­lab­o­ra­tion be­tween Japan and France. The main pur­pose is un­manned and dust-free op­er­a­tion in clean room to avoid per­for­mance degra­da­tion with field emis­sion in ver­ti­cal test and cry­omod­ule test. The ver­ti­cal auto clean­ing sys­tem and the re­place­ment sys­tem be­tween blank flange and bel­lows have been op­er­ated suc­cess­fully in 2021-2022. Cur­rently, clean work stud­ies re­lated to auto clean­ing and as­sem­bly is under progress by com­bin­ing the blank-bel­lows re­place­ment sys­tem and a robot arm. In this re­port, the re­cent sta­tus of clean works at KEK will be pre­sented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB030  
About • Received ※ 17 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 30 June 2023
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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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WEIXA06 Recent Advances in Metallographic Polishing for SRF Application 646
 
  • O. Hryhorenko
    JLab, Newport News, Virginia, USA
  • C.Z. Antoine, F. Éozénou, Th. Proslier
    Université Paris-Saclay, CEA, Gif-sur-Yvette, France
  • T. Dohmae
    KEK, Ibaraki, Japan
  • S. Keckert, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • D. Longuevergne
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  Funding: ENSAR-2 under grant agreement N° 654002. IFAST under Grant Agreement No 101004730. The U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
This talk is an overview of the met­al­lo­graphic pol­ish­ing R&D pro­gram cov­er­ing Nio­bium and Cop­per sub­strates treat­ment for thin film coat­ing as an al­ter­na­tive fab­ri­ca­tion path­way for 1.3 GHz el­lip­ti­cal cav­i­ties. The pre­sented re­search is the re­sult of a col­lab­o­ra­tive ef­fort be­tween IJ­CLab, CEA/Irfu, HZB, and KEK in order to de­velop in­no­v­a­tive sur­face pro­cess­ing and cav­ity fab­ri­ca­tion pro­to­cols ca­pa­ble of meet­ing strin­gent re­quire­ments for SRF sur­faces, in­clud­ing the re­duc­tion of safety risks and eco­log­i­cal foot­print, en­hanc­ing re­li­a­bil­ity, im­prov­ing the sur­face rough­ness, and po­ten­tially al­low­ing cost re­duc­tion. The re­search find­ings will be dis­closed. 		 
slides icon Slides WEIXA06 [7.469 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEIXA06  
About • Received ※ 16 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 14 July 2023
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WEPWB050 Exploring Innovative Pathway for SRF Cavity Fabrication 680
 
  • O. Hryhorenko
    JLab, Newport News, Virginia, USA
  • C.Z. Antoine
    Université Paris-Saclay, CEA, Gif-sur-Yvette, France
  • T. Dohmae
    KEK, Ibaraki, Japan
  • D. Longuevergne
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Funding: ENSAR-2 under grant agreement N° 654002. The U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
This ar­ti­cle shows a study on an al­ter­na­tive path­way for the fab­ri­ca­tion of a com­plete 1.3 GHz SRF cav­ity, aim­ing at im­prov­ing pro­duc­tion re­li­a­bil­ity, re­duc­ing the use of chem­i­cal pol­ish­ing (EP or BCP) which is a costly and safety-crit­i­cal step, and pre­serv­ing sur­face qual­ity after form­ing. Un­like the con­ven­tional path­way, the fab­ri­ca­tion process is per­formed after pol­ish­ing. This point is cru­cial as the used pol­ish­ing tech­nol­ogy could be ap­plied only to flat geome­tries. The per­formed in­ves­ti­ga­tion demon­strates that dam­ages dur­ing the fab­ri­ca­tion process are con­sid­ered minor, lo­cal­ized, and lim­ited to the near-sur­face. More­over, these stud­ies con­firm that the dam­aged layer (100-200 µm) is mainly caused by the rolling process, and not by the sub­se­quent fab­ri­ca­tion steps. A laser con­fo­cal mi­cro­scope and SEM-EBSD tech­nique were used to com­pare sam­ples be­fore and after form­ing. The pre­lim­i­nary re­sults are dis­cussed and pre­sented in this paper. 		 
poster icon Poster WEPWB050 [2.263 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB050  
About • Received ※ 20 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 01 July 2023
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THCAA01 Development of Single-spoke Cavities for ADS at JAEA 947
 
  • Y. Kondo
    JAEA, Ibaraki-ken, Japan
  • T. Dohmae, E. Kako, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  • F. Maekawa, S.I. Meigo, J. Tamura, B. Yee-Rendón
    JAEA/J-PARC, Tokai-mura, Japan
  
  Japan Atomic En­ergy Agency (JAEA) has been propos­ing an ac­cel­er­a­tor-dri­ven sys­tem (ADS) as a fu­ture nu­clear sys­tem to ef­fi­ciently re­duce the high-level ra­dioac­tive waste gen­er­ated at nu­clear power plants. As the first step to­ward the full-scale CW pro­ton linac for the JAEA-ADS, we are now pro­to­typ­ing a low-beta (around 0.2) sin­gle-spoke cav­ity. Be­cause there is no ex­pe­ri­ence in man­u­fac­tur­ing su­per­con­duct­ing spoke cav­i­ties in Japan, pro­to­typ­ing and per­for­mance test­ing of the cav­ity are es­sen­tial to en­sure the fea­si­bil­ity of the JAEA-ADS. The di­men­sional pa­ra­me­ters of the pro­to­type spoke cav­ity were op­ti­mized to ob­tain higher cav­ity per­for­mance. The ac­tual cav­ity fab­ri­ca­tion started in 2020. Most of the cav­ity parts were fab­ri­cated in fis­cal year 2020 by press-form­ing and ma­chin­ing. In 2021, we started weld­ing the cav­ity parts to­gether. After in­ves­ti­gat­ing the op­ti­mum weld­ing con­di­tions using mock-up test pieces, each cav­ity part was joined with smooth weld­ing beads. Cur­rently, the cav­ity’s body sec­tion and the beam port sec­tions have been as­sem­bled. This paper pre­sents the cur­rent sta­tus of the JAEA-ADS and it’s cav­ity pro­to­typ­ing.  
slides icon Slides THCAA01 [8.433 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-THCAA01  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 10 July 2023
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