Generation of Runaway Electrons and X-ray at a Microsecond Voltage Rise Time in Different Gases

The results of studies of the generation of runaway electron beams and X-ray radiation in an inhomogeneous electric field in air, nitrogen, argon and helium under the pressures from 1 to 100 kPa are presented. The high-voltage generator producing a voltage pulse with an amplitude up to 200 kV and a rise time of ~ 1.5 μs was used. A runaway electron beam in helium at a pressure of 100 kPa was recorded with a collector. In air, nitrogen, and argon, a runaway electron beam had relatively small amplitudes and energies, and was recorded by the collector only at low pressures (<; 20 kPa). X-ray radiation behind an aluminum foil anode for all four gases in the total pressure range was detected with a scintillator and a PMT. For a microsecond voltage rise time, it is necessary to use cathodes providing the highest voltage of the gap breakdown.