Comparison of Germanium-Stainless Steel Electrode Configurations for Possible Utilization in Electric Discharge HF Lasers

摘要

An HF laser cavity was designed and constructed in which four electrode combinations were tested. The electrodes consisted of two stainless steel Chang-profiled electrodes and two 50-omega cm germanium electrodes. The four possible electrode combinations for anode and cathode were tested. Breakdown, sustaining, and arcing voltages were recorded, for each combination, over a range of 25-200 pulses per second for the following gases with their respective pressure ranges: helium, 50-90 Torr; nitrogen, 5-30; sulfur-hexafluoride, 3-15 Torr. The use of germanium as a cathode material resulted in substantially greater suppression of arc formation than the use of stainless steel. Helium, which sustained arcs at 60 Torr and 100 pps with a stainless steel cathode-anode, was found to be arc-free at pressures up to 90 Torr with repetition rates as high as 200 pps using a germanium cathode. similarly, sulfur-hexafluoride, which sustained arcing at 3 Torr and 150 pps with stainless steel electrodes was found to be arc-free at pressures over 13 Torr when germanium was used as a cathode. The use of germanium as both anode and cathode resulted in the highest suppression of arc formation. (Author)