Record capture and acceleration efficiency in the SURF-II 300 MeV circular storage ring

SURF-II is a 300-MeV, single-magnet, weak-focusing, circular storage ring. It is dedicated to the production of VUV (vacuum ultraviolet) and soft X-ray radiation for research and for absolute radiometry. The injector is a 10-MeV microtron. A single output pulse from the microtron is injected into the storage ring (SR) and accelerated to operating energy., The microtron delivers 1- mu s-long, 80-mA pulses. With multiturn capture, more than 300 mA have been accelerated to full energy. On March 13, 1989, the average beam current was 262 mA and every beam was greater than 250 mA. This capture and acceleration efficiency is being achieved by improved transport line optics, the kicker magnet pulse, the SR's magnetic field gradient, and the RF system.<>