Investigation of the Statistical and Formative Time Lags Associated with the Breakdown of a Gas in a Gap at High Overvoltage

The results of an investigation of the statistical behavior of the observational time lag to breakdown in an overvolted sparkchamber are presented as a function of pressure (up to 1350 torr of nitrogen), electrode separation (1 and 2 cm) and percent overvoltage (up to 2800 percent). Rogowski contoured, graphite, brass, and aluminum electrodes have been investigated. Automated diagnostic equipment has allowed the reduction of large amounts of data. The results indicate: 1) the shapes of the distributions are strong functions of pressure, 2) the electron emission rate associated with graphite is an order of magnitude greater than that associated with aluminum and brass, 3) the cathode emission rate is much higher than the "apparent" rate determined from a simple stochastic model, and 4) the formative time (taken as the minimum observed time lag) is an order of magnitude greater than that predicted by the streamer model of breakdown.