The spectra of electron beams produced in air-filled diodes at atmospheric pressure

It is shown that the breakdown of a gap with a small-curvature-radius cathode by a voltage pulse with an amplitude of >100 kV and a rise time of about 0.3 ns is accompanied by the generation of runaway electrons with energies from a few keV to several hundred keV. In the electron spectrum, three groups of electrons with different energies can be distinguished. It is shown that the energy spectrum of the beam electrons depends on the voltage rise time, voltage amplitude, and cathode design.