Circuit and plasma simulation for the design of ZT-40

ZT-40, a toroidal Z pinch, uses its driving circuits to produce programmed magnetic fields. The field profiles must lie within certain bounds in order to meet the criteria imposed by the physics. The driving circuit design is complicated by the strong influence of the plasma on the circuit performance. The plasma appears to the driving circuit as time varying inductance and resistance. Since the inductance comprises from 20 to 80% of the total inductance, depending on the plasma configuration and the circuit, driving circuit performance is not easily calculated. The ZT-40 field requirements are presented and the proposed circuits are discussed. The modeling used to include the plasma as an electrical component with time varying inductance and resistance is described. The results of representative calculations are given