• T. Adachi, T. Kawakubo
  KEK, Ibaraki
• T. Yoshii
  Nagaoka University of Technology, Nagaoka, Niigata

New acceleration system using an induction cell has been developed at KEK by using KEK 12-GeV PS*. We call an accelerator using the induction acceleration system "Digital Accelerator". The PS-Booster is now being renovated as the first Digital Accelerator (DA) by introducing the induction acceleration instead of rf**. Argon ion beam from the ECR ion source is injected to the DA by an electrostatic beam kicker. Another electrostatic device with the same structure is used for chopping the beam before injection. The accelerated beam is extracted by the existing extraction system, which comprises bump, septum and kicker magnets. Since these magnets are installed in a vacuum chamber, vacuum pressure deteriorates due to outgas from them. In order to reduce a beam loss in the DA ring, the pressure level is crucial especially for an ion beam. Therefore, we decided to put the septum magnet outside the vacuum chamber and insert a vacuum duct in the gap, since it dominantly contributes to the vacuum pressure more than the other magnets. This paper describes the electrostatic beam chopper, injection kicker and septum magnet containing the vacuum duct for the KEK DA and beam dynamics.

*K. Takayama, Phys. Rev. Lett. 98, 054801 (2007)
**K. Takayama, "KEK Digital Accelerator for Material and Biological Sciences", T. Iwashita, "Induction Acceleration System", 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.