A digital, Nyquist solving, feedback control system for ZTP

Summary form only given. It is proposed that the ZTP (a small reversed field pinch) equilibrium feedback controller be built around a PC and a DSP (digital signal processing) board. Initially, ZTP will be operated with a passive equilibrium system which already maintains excellent discharge position. A nominal feedback response will then be programmed into the DSP board so the feedback system will attempt to improve the equilibrium position. During each successive plasma discharge, the input and output signals will be recorded. These signals will be processed between shots by the PC to determine the forward transfer function of the entire equilibrium system. As the knowledge of the forward transfer function is improved, the system will recalculate an appropriate feedback transfer function that satisfies the Nyquist criterion. The intent of this procedure is to develop a feedback transfer function program in the DSP board which is progressively improved as the knowledge of the forward transfer function is increased. As the feedback transfer function is refined, the gain and frequency response can be increased, which will improve the position control. By this means, one can achieve a highly accurate, fast, and stable feedback system for ZTP, which may also be applicable to the ZTH experiment presently being built at Los Alamos National Laboratory