Design of the ZT-1 toroidal pinch experiment

Electrical design details are given for a toroidal Z-pinch device named ZT-1 that uses field programming to achieve a stable, reversed field pinch. The plasma is formed in a 4-mm-thick, 10.3-cm-i.d., high alumina, segmented ceramic vacuum chamber. Voltages as high as 70 kV are routinely attained by interrupting with a fuse 800 kA in an inductive store. The current is diverted from the fuse to the primary of a single-turn transformer divided into quadrants. A total of 280 kV at 200 kA can then be applied to the plasma, which forms the secondary circuit of the transformer. This system produces dB/sub theta//dt's of up to 8 T/ $mu$s; with modifications to the electrical system, dB/sub theta//dt's as low as 0.1 T/$mu$s are obtained. The B/sub z/ bias field of up to 0.25 T can be reversed at a rate of up to 0.2 T/$mu$s. Both B/sub theta/ and B/sub z/ magnetic field errors are minimized. The design of the fuses and magnetic core and the development of a low inductance and resistance metal-to-metal crowbar are described. (auth