Recovery of a high pulse rate spark gap switch

A study of purged spark-gap recovery at high pulse rates is reported. This work was part of an evaluation of an innovative approach for configuring the flow channel of a high-pulse-rate spark gap to control unsteady flow processes so that recovery can be near 100% and very repeatable. The switch and purge-flow-channel geometry are configured to utilize the unsteady flows and pressure disturbances in order to augment recovery. Tuned unsteady flow is used to provide purging of the hot gas residue at an adequate distance from the spark gap while simultaneously restoring the gas density between the electrodes to the initial values at the time of subsequent pulses. It is found that the unsteady fluid dynamic model provides a very good description of the recovery process for a high-pulse-rate spark gap. The model predictions show very good agreement with data from high-voltage recovery tests. The modeling and tests were used to evaluate the tuned gap concept, specify a test switch design, and characterize operation at high repetition frequencies. The tuned unsteady-flow configuration operated as expected, with full recovery of the test spark gap demonstrated at pulse rates to approximately 2500 Hz