KEK digital accelerator

Abstract

The High Energy Accelerator Research Organization KEK digital accelerator (KEK-DA) is a renovation of the KEK 500 MeV booster proton synchrotron, which was shut down in 2006. The existing 40 MeV drift tube linac and rf cavities have been replaced by an electron cyclotron resonance (ECR) ion source embedded in a 200 kV high-voltage terminal and induction acceleration cells, respectively. A DA is, in principle, capable of accelerating any species of ion in all possible charge states. The KEK-DA is characterized by specific accelerator components such as a permanent magnet X-band ECR ion source, a low-energy transport line, an electrostatic injection kicker, an extraction septum magnet operated in air, combined-function main magnets, and an induction acceleration system. The induction acceleration method, integrating modern pulse power technology and state-of-art digital control, is crucial for the rapid-cycle KEK-DA. The key issues of beam dynamics associated with low-energy injection of heavy ions are beam loss caused by electron capture and stripping as results of the interaction with residual gas molecules and the closed orbit distortion resulting from relatively high remanent fields in the bending magnets. Attractive applications of this accelerator in materials and biological sciences are discussed.

Wideband induction acceleration and its intrinsic nature in the KEK digital accelerator

“…[6]. Its machine and beam parameters, and its essential features directly related to the acceleration are summarized in this section.…”

“…A small-scale fast-cycling induction synchrotron (10 Hz), called the KEK Digital Accelerator (KEK-DA) [6], is now ready to accelerate many ion species and deliver them to users' lines. In this machine, heavy-ion beams, which are produced in the electron cyclotron resonance ion source (ECRIS) and accelerated with an extraction voltage of 200 kV, are injected into the ring by the electrostatic injection kicker.…”

Einzel lens chopper and behavior of the chopped beam in the KEK digital accelerator

“…In KEK-DA, an induction cell is employed as an acceleration device instead of a conventional RF cavity [1][2][3][4]. The concept of IS was demonstrated experimentally in 2006 [2] by using the KEK 12 GeV proton synchrotron.…”

“…Figure 1 shows the KEK-DA complex, where an ion beam produced in ECRIS [5] is extracted with a voltage of 10 kV and accelerated with a post-acceleration column with a voltage of 190 kV. The ion beam (He 1þ was utilized) propagates through the lowenergy beam transport line (LEBT), after which it is injected into the KEK-DA ring with an electrostatic (ES) kicker [1]. Since we use a single-turn injection method, the ES kicker must be turned off within the revolution time of the ion beam after injection.…”

“…The KEK digital accelerator (KEK-DA) is a small-scale induction synchrotron (IS) that was built as part of the renovation of the former KEK 500 MeV booster ring of the rapid-cycle proton synchrotron [1]. In KEK-DA, an induction cell is employed as an acceleration device instead of a conventional RF cavity [1][2][3][4].…”