Numerical simulation of spark channel dynamics in railgun switches

Discharge of a capacitive storage on a load with unipolar pulse is employed for pumping of powerful lasers and also for feeding of electromagnetic launchers, and pulsed high magnetic field facilities. Spark gaps are often used to commute energy on a load. In some applications unipolar pulse is not feasible and oscillatory regime (underdamped sinusoidal) has to be realized for the capacitor bank discharge. Spark gaps, developed for unipolar discharge, cannot directly be employed in under-damped (oscillatory) regime, because at current transition through zero the arc channel could stop motion and ignite at initial place on the following half period. Two main objectives were pursued in this work: 1. develop and test simulation model of a the spark channel motion in linear rail geometry for the oscillatory regime of capacitor bank discharge; 2. Investigate arc motion and electrodes heating depending on the current and charge transfer in wide operation range. (paper)