Fig. 1. Experimental layout of triple-pulse vacuum surface flashover

Fig. 2. Typical single-pulse experimental waveform

Fig. 3. Steps of surface flashover experiment

Fig. 4. Vacuum flashover voltage and electric strength of XLPS with different thickness under single pulse

Fig. 5. Vacuum flashover voltages of XLPS under single pulse and triple pulse loading

Fig. 6. Pulse top drop waveforms under higher sample voltage

Fig. 7. Three-pulse waveform at lower sample voltage

Fig. 8. Three-pulse waveform at higher sample voltage

Fig. 9. Three pulse waveform after pulse A flashover

Fig. 10. Theoretical model of secondary electron emission avalanche