Performance Characteristics of a 1 MV Miniature Marx Bank

In this paper we report results of experiments with a compact Marx bank generator. The Marx was constructed with 25 spark-gap switched stages, each stage consisting of two Murata 2 nF capacitors with N4700 ceramic dielectric rated at 40 kV. In order to evaluate the Marx efficiency and repetition rate, inductive isolation with 5 uH per stage was implemented for the charging circuit. The Marx was charged with a 1500 Js capacitor charging power supply. The system was controlled and monitored with a laptop computer through a fiber optic interface. We report results from operating the Marx from one quarter to full output voltage , nominal 250 kV to 1 MV open circuit OC. Short duration testing showed that the Marx could be triggered continuously at a repetition rate varying from 20 to 50 Hz, depending on the charging voltage. Various representative loads were used for diagnostic purposes and for comparison to modeling efforts. When operated into a short circuit, the Marx current oscillated at 14 MHz with a peak amplitude of about 10 kA. The Marx was also operated with and without a coaxial ground enclosure to investigate the influence of this geometry on pulse characteristics. We compare the results of circuit modeling with the experimental measurements and show good agreement.