Development of a feedback control system for magnet power supplies using EPICS EPID at KEK injector linac

The KEK injector linac provides the electron and positron beams of different energies for the PF, PF-AR and KEKB rings. Towards SuperKEKB project, the new quadrupole magnets and power supplies have been installed in the positron capture beam line. We have a plant to control the new power supplies with a constant voltage control mode since they show the current oscillation under a constant current control mode. For this purpose, a new power supply control IOC using EPICS EPID record is developed for the PID feedback control. In this paper, we report the new power supply control IOC and its test result in detail. (author)