Computing hardware for the PBX-M Plasma Control System

This paper describes architectural and performance aspects of the digital computer control system used for the PBX-M Plasma Control System (PPCS). The goal of the PPCS is to achieve integrated and improved plasma control. Integration consists of replacing control functions presently served by several analog systems with a realtime digital control system. The inherently dynamic control capabilities of a high performance digital system foster exploration of advanced plasma control concepts to serve future tokamaks. The PPCS runs concurrent multiple feedback control loops, with input, processing, and output times ranging from 100 /spl mu/S to 10 milliseconds. The initial control loop for plasma shaping was expected to complete in approximately 300 /spl mu/S. The VME-based realtime computing hardware is described. In addition, measurements of the system's performance such as data i/o rates and computing performance are shown. The information presented herein covers the results of the computer system's design, configuration, and laboratory testing. Actual plasma control has not been accomplished to date.