The Electrical Breakdown of Vacuum Insulated Electrodes under Radio Frequency Stress

The electronic and ionic theories of vacuum breakdown under the influence of RF fields are discussed. Theoretical calculations indicate that phenomena involving electrode ions in gaps of 0.2 cmandlargerare strongly influencedby time varying fields in the frequency range of 20 to 120 MHz. Similar gap conditions do not significantly alter breakdown when only field emission electrons are considered. Experimental equipment which can compare breakdown at RF to that at 60 Hz has been constructed. The results of experiments at 21. 4 MHz are best predicted by the electron theories of vacuum breakdown.