Plasma Switching Using a Capacitive Discharge Technique

Current interruption for plasmas is normally a relatively slow business since the switch-off time is controlled by the deionization time for the plasma under zero E-field condition. By using a separate electrode with a reverse current, the cathode spot can be interrupted and the switch off proceeds. The time can be considerably decreased by the continued presence of the E field between anode and cathode. A cold-cathode mercury arc was investigated at currents up to 30 A, but the technique should be applicable for even higher currents. Current interruption with this technique is shortened, but the exact switch-off time is dependent on where the measurement is made and what is defined as interruption.