CONTROL CHARACTERISTICS OF THE PEFP RF SYSTEM

A 20 MeV proton accelerator has been developed and tested at Proton Engineering Frontier Project (PEFP) as a front-end part of the 100 MeV accelerator. The initial test results showed that more stable RF operation was necessary to investigate the machine characteristics more comprehensively. A LLRF control system using commercially available digital board was newly developed and tested for this purpose. The goals of the RF control for 20 MeV accelerator are to achieve errors within 1% in amplitude and 1 degree in phase against external perturbations such as change of resonant frequency, fluctuation of klystron power supply voltage and also beam loading. In addition, the PEFP 20 MeV DTL has unique characteristics that single klystron drives four independent tanks simultaneously. In this paper, the initial test results of the RF system with digital controller are presented and its control characteristics are discussed.