Arc dynamics in high current rails park gaps

Summary form only given: Large capacitive energy storage systems are being implemented for powerful laser systems, electromagnetic launchers, and other pulsed power systems. Such MJ-class modularized capacitor banks individually require precise, reliable, cost-effective, and robust closing switches for synchronous operation. The closing switch, under intense mechanical and thermal shocks imposed by the high peak current, must tolerate high charge transfer, and provide long service life. The most popular closing switches up to date are spark gaps due to relatively simple design, robustness, easily field maintenance and repair. Main drawback of spark gaps is limited lifetime, which is related directly or indirectly to erosion of the electrodes. Various types of switches have been introduced, which utilize principle of arc motion in a magnetic field, thus effectively decreasing the current density on the switch electrodes. Three-electrode gas switches with electrodynamical acceleration of a spark channel have been developed in the Institute of High Current Electronics, Tomsk [1]. In such switches at a given current amplitude the diameter of the extended electrodes allows to control the spark velocity and hence the erosion of the electrodes providing the required lifetime. This report deals with numerical calculations of arc motion and electrodes erosion in rail spark gap. Results of numerical calculations are compared with experimental results in the report. Conditions for reduced electrodes erosion are defined.