Conditioning phenomenon in vacuum discharge

Experimental data on electric breakdown in a 0.35 mm high-vacuum gap due to rectangular high-voltage pulses is presented. In one system vacuum was achieved using an oil diffusion pump, in the other, using an ion-sorption pump.It is shown that oil vapor and the cracking products of the oil formed during breakdown affect the probability distribution of breakdowns. Conditioning is linked to the dynamic processes of rupture and of reestablishing initiating centers on the electrode surface. A physical model is suggested for the conditioning processes.