For reliable operation and component protection, of the 2 MW 30 120 MHz ICRF amplifier system on DIII D, it is desirable for the amplifier to respond to high VSWR conditions, resulting from plasma variations, as rapidly as possible. This requires a rapid change in power which also means a rapid change in the high voltage power supply current demands. An analysis of the power supply s regulator dynamics was preformed to evaluate its expected operation during such conditions. Based on this study it was determined that a new regulator with a larger dynamic range and some anticipation capability is required.

This paper will discuss the system requirements, the as-delivered regulator performance, and the improved performance after installation of the new regulator system. It will also be shown how this improvement has made the amplifier perform at higher power levels more reliably.

*Work supported by U.S. Department of Energy Contract DE-AC03-89ER51114.