Surface Aging in High Repetition Rate Spark Switches with Aluminum and Brass Electrodes

The surface aging of the electrodes of miniature spark switches (A/d ~ 50) is explored using commercial dry nitrogen as the working gas. Both brass and aluminum electrodes were investigated for aging characteristics using a constant gas flow rate of 8 cm3/s. The gas pressure was varied from 760 torr-5200 torr. The switches were constructured as an integral part of a miniature LC oscillator which has a ringing frequency of approximately 150 MHz. The aging process was halted at intervals ranging from one to several thousand discharges and the electrode surface examined with a scanning electron microscope.