Short circuit tests on a 150 kJ, 1 Hz repetitive plasma focus

This work presents the results of short circuit tests recently conducted on PFMA1 [1], a 150 kJ Mather-type Plasma Focus [2] designed to run at a repetition rate of 1 Hz for two hours at a time. PFMA1 is operated at 30 kV, with a 350 µF capacitor bank of 32 parallel capacitors. It is equipped with a custom designed fast high-voltage capacitive probe, a Rogowski coil [3] to monitor the total current ?owing from the capacitor bank, and a breakdown time jitter analyzer. The short-circuit tests are conducted at 12-13 kV. Snowplow-type 2D simulations [4] predict a peak of approximately 1.5 MA for the total current at a filling pressure of 10 Torr of deuterium. In this work a description of PFMA1 will be given, together with analytical computations of the inductance of the device; these computations will be compared with the results from a 2D finite element model in cylindrical symmetry. A full description of the electrical diagnostics used in the experiments will be provided. experimental results will be presented and discussed, and will be compared with those obtained theoretically. Agreement is found to be very good.