Author: Ezura, E.
Paper Title Page
MOPC019 Condition of MA Cut Cores in the RF Cavities of J-PARC Main Ring after Several Years of Operation 107
 
  • M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • E. Ezura, K. Hasegawa, K. Takata
    KEK, Tokai, Ibaraki, Japan
  • K. Hara, C. Ohmori, M. Toda, M. Yoshii
    KEK/JAEA, Ibaraki-Ken, Japan
  • T. Sato, M. Yamamoto
    JAEA, Ibaraki-ken, Japan
  
  J-PARC 3 GeV RCS and 50 GeV Syn­chrotron (MR) em­ploy RF cav­i­ties load­ed with Mag­net­ic Alloy (MA) cores to gen­er­ate a high field gra­di­ent. The RF cav­i­ties in RCS use MA un-cut cores. On the other hand, the RF cav­i­ties in MR em­ploy MA cut cores to in­crease the Q-val­ue from 0.6 to 26. We ob­served the impedance re­duc­tions of all MR RF cav­i­ties dur­ing sev­er­al years op­er­a­tion. Open­ing the RF cav­i­ties, we found that the impedance re­duc­tions were re­sult­ing from cor­ro­sion on the cut and pol­ished sur­faces of MA cores. Be­fore in­stal­la­tion of the RF cav­i­ties, we had 1000 and 2000 hours long tests at a test stand. We didn't ob­serve the impedance re­duc­tion re­lat­ed to the cor­ro­sion on the MA core cut sur­faces at the test stand. The only dif­fer­ence be­tween the test stand and MR is the qual­i­ty of cool­ing water. The MR cool­ing water con­tains cop­per ions for ex­am­ple from cop­per hol­low con­duc­tors of the main mag­nets. We re­port the in­flu­ence of the cop­per ions to the cor­ro­sion on the MA core cut sur­face. We also show plans how to solve the issue of MA core cut sur­face cor­ro­sion.  
 
MOPS008 Simulation of Longitudinal Emittance Control in J-PARC RCS for 400 MeV Injection 607
 
  • M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  
  The in­jec­tion en­er­gy up­grade of the J-PARC RCS from 181 MeV to 400 MeV is sched­uled, this is nec­es­sary to achieve the de­sign beam in­ten­si­ty. The high in­ten­si­ty beam is de­liv­ered to the MR, and the space charge ef­fect at the MR in­jec­tion should be al­le­vi­at­ed by op­ti­miz­ing the lon­gi­tu­di­nal beam emit­tance at RCS ex­trac­tion. This is re­al­ized by match­ing the shape of the beam emit­tance be­tween the RCS and the MR. We de­scribe the re­sults of par­ti­cle track­ing sim­u­la­tion with the lon­gi­tu­di­nal emit­tance con­trol dur­ing the whole ac­cel­er­a­tion pe­ri­od of the RCS.  
 
WEPS010 Acceleration of High Intensity Proton Beams in the J-PARC Synchrotrons 2502
 
  • M. Yoshii
    KEK/JAEA, Ibaraki-Ken, Japan
  • E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, K. Takata, M. Toda
    KEK, Tokai, Ibaraki, Japan
  • T. Minamikawa
    University of Fukui, Fukui, Japan
  • M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
  
  The J-PARC ac­cel­er­a­tor com­plex con­sists of the linac, the 3GeV rapid cy­cling syn­chrotron (RCS) and the 50GeV main syn­chrotron (MR). These syn­chrotrons are the first MW-class pro­ton ac­cel­er­a­tors which em­ploy the high elec­tric field gra­di­ent mag­net­ic alloy (MA) load­ed RF cav­i­ties. The beam com­mis­sion­ing was start­ed in Oc­to­ber 2007 for RCS and in May 2008 for MR. High in­ten­si­ty beam op­er­a­tion stud­ies and user runs have been per­formed, while care­ful­ly con­trol­ling and min­i­miz­ing the beam loss. The cycle to cycle beam op­er­a­tion is re­pro­ducible and quite sta­ble, be­cause of the sta­ble linac beam en­er­gy and the re­pro­ducible bend­ing field in both syn­chrotrons. The MA load­ed RF sys­tems and the full dig­i­tal LLRF also guar­an­tee the sta­ble lon­gi­tu­di­nal par­ti­cle mo­tion and pre­cise beam trans­fer syn­chro­niza­tion from RCS to the MLF user fa­cil­i­ty as well as to the MR. A high in­ten­si­ty pro­ton beam of 2.5·1013 ppp is ac­cel­er­at­ed in RCS. And in MR, a beam in­ten­si­ty up to ~100 Tera ppp was ob­tained.　We sum­ma­rize the RF sys­tems and the lon­gi­tu­di­nal pa­ram­e­ters in both rings.  
 
THOBB02 High Gradient Magnetic Alloy Cavities for J-PARC Upgrade 2885
 
  • C. Ohmori, O. Araoka, E. Ezura, K. Hara, K. Hasegawa, A. Koda, Y. Makida, Y. Miyake, R. Muto, K. Nishiyama, T. Ogitsu, H. Ohhata, K. Shimomura, A. Takagi, K. Takata, K.H. Tanaka, M. Toda, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • T. Minamikawa
    University of Fukui, Fukui, Japan
  • M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
  
  Mag­net­ic alloy cav­i­ties are used for both MR and RCS syn­chrotrons. Both cav­i­ty sys­tems op­er­ate suc­cess­ful­ly and they gen­er­ate a high­er volt­age than could be achieved by an or­di­nary fer­rite cav­i­ty sys­tem. For the fu­ture up­grade of J-PARC, a high­er RF volt­age is need­ed. A new RF cav­i­ty sys­tem using the ma­te­ri­al, FT3L, is de­signed to achieve this high­er field gra­di­ent. A large pro­duc­tion sys­tem using an old cy­clotron mag­net was con­struct­ed to an­neal 85-cm size FT3L cores in the J-PARC Hadron Ex­per­i­ment Hall. The muSR (Muon Spin Ro­ta­tion/Re­lax­ation/Res­o­nance) Ex­per­i­ments were also car­ried out to study the mag­net­ic alloy. The sta­tus of de­vel­op­ment on the J-PARC site and a new RF sys­tem de­sign will be re­port­ed.  
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