Development of a triple-path, low-inductance, low-voltage spark gap switch

We report on the development and testing of a triple-path, low-inductance, low-voltage, high-current, field-distortion spark gap switch as one of the key technologies in developing the next-generation coaxial plasma gun for plasma jet driven magneto-inertial fusion. The gas chamber of the spark gap switch has been designed to harbor three electrically isolated, parallel electrical paths to achieve low inductance, while synchronization improvement is achieved through the use of radiation from the arc discharges when any of the gaps break down. Paschen's breakdown curve of the triple-path spark gap switch has been measured with gas pressure ranging from 0.1 to 2.5 BarG to validate the performance of the switch. The delay time and jitter of the spark gap switch have been measured on a dedicated switch test stand as well as in the single-shot plasma-gun-firing experiments at operating voltages of 5 kV and peak currents as high as 0.25 MA. The triple-path spark gap switches have demonstrated high stability and reproducibility in these experiments, with the jitter of the total current being 66 ns over 350 shots.