Erratic gas breakdown at high pressures

It is acknowledged that the electric strength of a gas at high pressure is not a well-defined parameter and that virgin electrodes in such a gas need to be conditioned by sparking before a high strength can be realized. Even then, sporadic breakdown of the gas may still occur at very much lower stresses, a fact which, together with conditioning, many authors ignore in discussing the mechanisms of breakdown. These findings, together with the failure of Paschen's law at high pressure, mean that the normally acceptable theories of gas breakdown cannot apply directly at high pressures. It is the purpose of this paper to summarize experiments made to elucidate some of the processes which cause these departures from classical behavior.