• K. Hasegawa, T. Kobayashi, Y. Kondo, T. Morishita, H. Oguri
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• Y. Hori, C. Kubota, H. Matsumoto, F. Naito, M. Yoshioka
  KEK, Ibaraki

The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) ac­cel­er­ates a beam from the ion source to the DTL. The beam test of the linac was start­ed in Novem­ber 2006 and 181 MeV beam was suc­cess­ful­ly ac­cel­er­at­ed in Jan­uary 2007. Since then, the linac has been de­liv­ered beams for com­mis­sion­ing of the linac it­self, down­stream ac­cel­er­a­tors and fa­cil­i­ties. Trip rates of the RFQ, how­ev­er, un­ex­pect­ed­ly in­creased in Au­tumn 2008, and we have been suf­fer­ing from this issue for user run op­er­a­tion since then. We tried to re­cov­er by ten­der con­di­tion­ing, mod­i­fi­ca­tion of RF con­trol, im­prove­ment of vac­u­um prop­er­ties and so on. By tak­ing these mea­sures, we man­age to have 2 to 3 days con­tin­u­ous beam op­er­a­tion. In this re­port, we de­scribe the sta­tus of the RFQ.

• Y. Kondo, K. Hasegawa, T. Morishita
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• H. Matsumoto, F. Naito
  KEK, Ibaraki

A new RFQ for the J-PARC linac is under con­struc­tion for more sta­ble op­er­a­tion. The re­quire­ment of this RFQ is al­most same as the now-op­er­at­ing one; the res­o­nant fre­quen­cy is 324MHz, the in­jec­tion en­er­gy is 50 keV, the ex­trac­tion en­er­gy is 3 MeV, peak beam cur­rent is 30 mA, and RF duty is 1.5%. The res­o­nant fre­quen­cy tun­ing dur­ing op­er­a­tion will be done by ad­just­ing the tem­per­a­tures of the cool­ing wa­ters. In this paper, ther­mal char­ac­ter­is­tics of this RFQ and con­trol sys­tem of the cool­ing water tem­per­a­ture is de­scribed.

• T. Morishita, K. Hasegawa, Y. Kondo
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• H. Baba, Y. Hori, H. Kawamata, H. Matsumoto, F. Naito, Y. Saito, M. Yoshioka
  KEK, Ibaraki

The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) ac­cel­er­ates a neg­a­tive hy­dro­gen beam from 0.05MeV to 3MeV to­ward the fol­low­ing DTL. As the trip rates of the prac­ti­cal­ly using RFQ in­creased in au­tumn 2008, we start­ed the prepa­ra­tion of a new RFQ as a back­up ma­chine. The beam dy­nam­ics de­sign of the new RFQ is the same as the cur­rent cav­i­ty, how­ev­er, the en­gi­neer­ing and RF de­signs are changed. The pro­cess­es of the vane ma­chin­ing and the sur­face treat­ments have been care­ful­ly con­sid­ered to re­duce the dis­charge prob­lem. The vac­u­um braz­ing tech­nique has been cho­sen for vane in­te­gra­tion. In this re­port, the de­tailed de­sign will be de­scribed with the progress of the fab­ri­ca­tion of the new RFQ.