An RF Acceleration Test for a Pulse Stretcher Ring. (1992)

点击翻译按钮获取中文摘要

An RF accelerating system for SSTR, the 150 Mev pulse stretcher ring at Tohoku University has been prepared and tested. An electron beam current of around 10 mA was stored for 3 seconds. The beam life was mainly limited due to a vacuum pressure of about 1x10^<-6> Torr at this time. An RF frequency of this accelerating system is 2856 MHz and is phase-locked to the master oscillator of the linear accelerator. A single-cell standing wave accelerating structure, which has a beam aperture diameter of 70 mm and four ports for RF couplers and resonant frequency tuners, has been completed. A shunt impedance of the structure was designed to be low and measured to be 0.26 megohms. An RF input coupler with coupling constant of 27.5 was designed and fabricated. These low impedance and high coupling constant have been optimized for a heavy beam loading change of 0 to 100 mA, which is repeated at 300 Hz. These RF parameters enable to suppress changes of accelerating voltage and phase within 1 % and 17 degrees, respectively, even if an input power of 250 watts is kept constant. No change in accelerating voltage and phase was observed when the beam current was changed from 0 to 10 mA within 100 nsec. The beam extraction from the ring is being planned for the next experiment.