Study of the RF Capture Process in the Argonne Rapid Cycling Synchrotron

The 500-MeV Rapid Cycling Synchrotron (RCS) guide field is energized by a dc-biased, 30 Hz sinusoidal ac power supply, and the field strength varies between 2.81-9.81 kG. During the acceleration period, the B varies in a half-sine function from zero to a maximum of 670 kG/s and back to zero. Although the average B during injection is not equal to zero, efficient capture has been obtained experimentally by adjustment of the RF voltage program and the injection timing. In this paper, we describe a simulation study of the capture process in order to understand the experimental results.