Cumulation effect of an electron beam generated in a high-voltage nanosecond discharge plasma in vacuum and gas diodes

Cumulation effect of a beam of runaway electrons formed in a high-voltage nanosecond discharge in air at pressures of 3-10(5) Pa and discharge gap length d of 1 - 5 mm was studied. Optimal conditions of the effect in discharge gap with a tubular potential cathode and grounded flat anode was achieved at an air pressure of similar to 5 Pa and d of 2.7 mm. An electron beam current pulse was recorded behind a foil anode with high (up to similar to 80 ps) time resolution. It was found that, due to the cumulation effect, a through hole is formed in an aluminum foil 20 mu m thick after 2-3 discharge pulses. The electron beam was found to register around the zone of maximum beam current density as well. As follows from the obtained results, energy of electrons of second part of electron beam current pulse is less than that of first part.