A Low Inductance 120 KV Energy Storage Module

A low inductance 120 kV energy storage module has been developed at the Naval Research Laboratory. Fifty of these modules operating in parallel will form the 300 kJ capacitor bank for the fast reversal field of the SWAP experiment. The module comprises two 60 kV, 1.85 μF capacitors operating as a modified Marx-type circuit. The self-inductance of the module, including the output switch and cable terminations, is approximately 110 nH. This arrangement has the advantage of using 60 kV power supplies, charging circuit and capacitors for a 120 kV capacitor bank and eliminates one of the series fast synchronized switches with a concomitant inductance reduction. The bank construction cost has been drastically reduced by the module physical arrangement. The second stage capacitor is mounted upside down directly on the first stage capacitor. The first stage capacitor therefore acts as both the support and insulator for the second stage capacitor whose case rises to 120 kV above ground at discharge.