• K. Takayama, T. Adachi, T. Arai, Y. Arakida, M. Hasimoto, T. Iwashita, E. Kadokura, M. Kawai, T. Kawakubo, K. Koyama, T. Kubo, T. Kubo, H. Nakanishi, K. Okamura, H. Someya, A. Takagi, M. Wake
  KEK, Ibaraki
• T. Kikuchi, T. Yoshii
  Nagaoka University of Technology, Nagaoka, Niigata
• K.W. Leo
  Sokendai, Ibaraki
• K. Mochiki, T. Sano
  Tokyo City University, Tokyo
• M. Okamura
  RBRC, Upton, Long Island, New York
• K. Okazaki
  Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture
• H. Tanaka
  Iwate university, Morioka, Iwate

A novel cir­cu­lar ac­cel­er­a­tor ca­pa­ble of ac­cel­er­at­ing any ions from an ex­treme­ly low en­er­gy to rel­a­tivis­tic en­er­gy is dis­cussed. A dig­i­tal ac­cel­er­a­tor (DA)* is based on the in­duc­tion syn­chrotron con­cept, which had been demon­strat­ed in 2006. All ions are cap­tured and ac­cel­er­at­ed with pulse volt­ages gen­er­at­ed by in­duc­tion ac­cel­er­a­tion cell (IAC). The IAC is en­er­gized by the switch­ing power sup­ply, in which power sol­id-state con­duc­tors are em­ployed as switch­ing el­e­ments and their tun­ing on/off is ma­neu­vered by gate sig­nals dig­i­tal­ly ma­nip­u­lat­ed from the cir­cu­lat­ing sig­nal of an ion beam. Ac­cel­er­a­tion syn­chro­nized with the rev­o­lu­tion of the ion beam is al­ways guar­an­teed. The con­cept is re­al­ized by ren­o­vat­ing the KEK 500 MeV boost­er into the DA, in­tro­duc­ing a laser ab­la­tion ion source. Ion en­er­gy of 85-140 MeV/au and in­ten­si­ty of 10⁺⁹ - 10⁺¹⁰ /sec are es­ti­mat­ed and these ions will be de­liv­ered with­out any large-scale in­jec­tor. Com­pan­ion pa­pers** will dis­cuss more de­tails of in­stru­ments of DA. Ap­pli­ca­tions for in­no­va­tive ma­te­ri­al sci­ences and life sci­ences will be briefly in­tro­duced as well as the out­line of DA.

*K. Takayam, J. of Appl. Phys. 101 (2007) 063304.
**K.Takayama "Ion source and LEBT", T.Adachi "Injection and extraction system", T.Iwashita "Induction acceleration system" in this conference.

• K. Takayama, T. Adachi, T. Arai, Y. Arakida, M. Hasimoto, T. Kawakubo, K. Koyama, T. Kubo, T. Kubo, H. Nakanishi, A. Takagi, K. Zhang
  KEK, Ibaraki
• T. Kikuchi
  Nagaoka University of Technology, Nagaoka, Niigata
• K.W. Leo
  Sokendai, Ibaraki
• K. Okazaki
  Nippon Advanced Technology Co. Ltd., Ibaraki-prefecture

KEK dig­i­tal ac­cel­er­a­tor (DA) ca­pa­ble of ac­cel­er­at­ing all species of ion* is an in­duc­tion syn­chrotron em­ploy­ing no large scale in­jec­tors. At the be­gin­ning of its op­er­a­tion, Ar ions from the ECR ion source (ECRIS) em­bed­ded in the 200 kV high volt­age ter­mi­nal (HVT) are di­rect­ly in­ject­ed into KEK-DA though the low en­er­gy BT line (LEBT). The per­ma­nent mag­net ECRIS was as­sem­bled at KEK. Its char­ac­ter­is­tics such as a charge-state spec­trum, emit­tance, and in­ten­si­ty are pre­sent­ed. The 200 kV HVT has been also as­sem­bled at KEK. Its volt­age sta­bil­i­ty in the pulse mode op­er­a­tion, where a plas­ma of 1 msec is cre­at­ed by x-band mi­crowaves at 10 Hz, is dis­cussed. The LEBT con­sists of the Eintzel lens, mo­men­tum an­a­lyz­er, B mag­nets with edge fo­cus­ing, elec­tro­stat­ic chop­per**, and a com­bi­na­tion of Q mag­nets. In the upper LEBT from the ion ex­trac­tion hall to the en­trance of the an­a­lyz­er, pos­si­ble charge-state ions are con­tam­i­nat­ed in the space-charge limit and beam fo­cus­ing is re­al­ized through the Eintzel lens and tan­dem ac­cel­er­a­tion gaps. In the lower LEBT from the an­a­lyz­er to the KEK-DA in­jec­tion point, the lat­tice has been op­ti­mized so as to meet op­tics match­ing at the in­jec­tion point.

*K. Takayama, J. of Appl. Phys. 101 063304(2007), "KEK digital accelerator for material and biological sciences" in this conference
**T.Adachi, "Injection and extraction system" in this conference

• Y. Irie, S. Fukumoto, K. Muto, H. Nakanishi, A. Takagi
  KEK, Ibaraki
• D. Bayley, I.S.K. Gardner, R.J. Mathieson, A. Seville, J.W.G. Thomason
  STFC/RAL/ISIS, Chilton, Didcot, Oxon
• J.C. Dooling, D. Horan, R. Kustom, M.E. Middendorf
  ANL, Argonne
• T. Oki
  Tsukuba University, Ibaraki

A low-out­put-impedance RF sys­tem for the sec­ond har­mon­ic cav­i­ty in the ISIS syn­chrotron has been de­vel­oped by col­lab­o­ra­tion be­tween Ar­gonne Na­tion­al Lab­o­ra­to­ry (US), KEK (Japan) and Ruther­ford Ap­ple­ton Lab­o­ra­to­ry (UK). The sys­tem has less than 30 Ω of out­put impedance over wide fre­quen­cy range of 2.7-6.2 MHz. How­ev­er, dis­tor­tions of volt­age wave­form in the driv­er stage have been a long-stand­ing issue. It was found such dis­tor­tions were gen­er­at­ed de­pend­ing upon the high­er-or­der-modes of the an­ode-choke impedance. In this re­port, method to re­al­ize the smooth si­nu­soidal wave­form in the wide­band sys­tem is pre­sent­ed.