• T. Iwashita, T. Adachi, T. Arai, Y. Arakida, M. Hasimoto, H. Someya, K. Takayama, M. Wake
  KEK, Ibaraki
• T.S. Dixit
  SAMEER, Mumbai
• K. Mochiki, T. Sano
  Tokyo City University, Tokyo

The KEK-DA (Dig­i­tal Ac­cel­er­a­tor) is a mod­i­fi­ca­tion of the KEK 500 MeV boost­er*, in which an in­duc­tion ac­cel­er­a­tion sys­tem is em­ployed. It has an abil­i­ty to ac­cel­er­ate ar­bi­trary ions with their pos­si­ble charge states**. An out­line of the ac­cel­er­a­tion sce­nario is de­scribed and a nec­es­sary con­trol sys­tem fully in­te­grat­ing the in­duc­tion ac­cel­er­a­tion sys­tem is given in de­tails. The KEK-DA is a rapid cycle syn­chrotron op­er­at­ing at 10 Hz; the ac­cel­er­at­ing pulse volt­age must be dy­nam­i­cal­ly var­ied in time to fol­low the ramp­ing mag­net­ic field. A novel tech­nique com­bin­ing the pulse den­si­ty con­trol and in­ter­mit­tent op­er­a­tion of ac­cel­er­a­tion cells is re­quired. The in­tel­li­gent gate con­trol sys­tem which uses 1 GHz dig­i­tal sig­nal pro­ces­sors (DSPs) has been de­signed. Con­struc­tion of the KEK-DA is in the final stage; in­stal­la­tion of the in­duc­tion cells and the power sup­plies are done. The whole sys­tem in­clud­ing gate con­trol sys­tem is demon­strat­ed with high volt­age out­puts,long-term sta­bil­i­ty of the sys­tem through a heat run is ex­am­ined. Also a fu­ture plan which re­places DSPs by FPGA (Field Pro­grammable Gate Array)is dis­cussed.

* K.Takayama et al., JOURNAL OF APPLIED PHYSICS 101, 063304 (2007).
** K.Takayama et al., "KEK Digital Accelerator for Material and Biological Sciences" in this conference.

• 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