Arbitrary pulse control for induction synchrotrons

Different form conventional RF synchrotrons, induction synchrotrons employ induction cells, which are one-to-one pulse transformers, for beam acceleration. The KEK digital accelerator, a small-scale induction synchrotron, can accelerate 50 keV/nucleon heavy ion beams injected directly from an electron-cyclotron-resonance (ECR) ion source and control the longitudinal beam bunch distribution with the pulse acceleration control. Digital signals from an Field-Programmable Gate Array (FPGA) control the switching timings of the switching power supplies (SPSs) energizing induction cells, and their signals are 50 msec long with a precision of <~3 ns. Recently, the development of more sophisticated beam control beyond the capability of the present FPGA control system has been critical to meet the demands of various beam acceleration schemes. This paper reports a new arbitrary digital pulse control system for induction synchrotrons with arbitrary pulse generators in detail. (author)