BREAKDOWN DEVELOPMENT OF PULSED N//2 AND SF//6 GAPS.

The discharge development of N//2 and SF//6 gaps has been investigated with a high-voltage cable pulse generator with a risetime of 1. 5 ns, a pulse width of 200 ns, and a maximum amplitude of 150 kV. To eliminate the statistical time lag, primary electrons have been generated by UV-illumination. One major result is that, for negative polarity in SF//6 , the formative time lags are mainly determined by the absolute value of the impulse voltage and are not significantly influenced by the various field distributions. In SF//6 , the dc breakdown voltage greatly decreases with the value of the degree of homogeneity in the test gap. The formative time lags in N//2 are found to be altered with the field distribution and develop asymptotically towards the corresponding dc breakdown voltage.