Change of the e-beam generation mode at transition from the vacuum to the gas-filled diode

In this paper, characteristics of the runaway electron beams downstream of a foil anode were studied at a pressure of helium, hydrogen, and nitrogen from vacuum to tens of torr. High-voltage pulses (~150 and ~250 kV) with pulse rise times of ~300 and ~500 ps were applied to the tubular cathode - plane anode gap. It is demonstrated that increasing the pressure from vacuum to 10 of torr and more changes the mode of the electron beam generation and can increase the beam current amplitude. It is shown that increasing the pressure of helium, hydrogen, and nitrogen allows continuously adjusting the electron beam duration from ~500 to ~100 ps (FWHM).