Breakdown in small, flowing gas spark gaps

An improved method for studying electrical breakdown in small, flowing gas spark gaps is described. The apparatus and data processing yield the time to breakdown, current, resistance, power dissipation and energy loss in the spark gap during the 4 nS in which the current rises from zero to a near constant value. A specially constructed transmission line terminated in a spark gap and instrumented with a B probe and sampling oscilloscope is used to observe the breakdown. The initial charge on the transmission line and the current, obtained by integrating the B signal, provide the information needed to define the spark gap operation in a well characterized coaxial arrangement. With a temporal resolution better than 50 pS, current components with frequencies to 10 GHz could be measured. An electronic circuit held the gap breakdown voltage and the subsequent charge in the transmission line to precise, predetermined values. A computer based data reduction system determined the current waveform from data corrected for the frequency response of the signal delay line. Results are given for argon and nitrogen, each at two overvoltages