Influence of the energy dependence of the electron distribution function on the stability of the electron beam - plasma system at Knudsen numbers of the order of 1

Within the framework of the kinetic approach, using the example of a low-voltage beam discharge in rare gases (LVBD), stability conditions are investigated depending on the temperature of the electron beam, the dispersion of the electron beam velocity in the direction of the discharge axis, and the form of the electron energy distribution function (EEDF). Regimes are considered when the inter-electrode distance is of the order of the electron mean free path relative to elastic collisions with rare gas atoms.

It is shown that the beam temperature, which is determined by the temperature of the heated cathode and does not exceed 1500 K, and the dispersion of the electron energy of the beam, which reaches 1 - 2 eV, have little effect on the conditions for the stability loss of the LVBD and the magnitude of the growth rate of disturbances at frequencies up to the plasma one. 

It was found that the form of the EEDF monotonically decreasing with increasing electron energy also does not affect the parameters of the perturbations propagating in the LVBD when the beam energy is much higher than the average electron energy in the plasma. The results obtained are applicable not only to LVBD, but also to other types of self-sustained beam discharges.