Electron Energy Distribution Function in a Discharge Afterglow in a He-Xe Mixture

Experimental and computational-theoretical studies of the electron energy distribution function (EEDF) at the afterglow stage of a glow discharge in a mixture of helium (content of 98.5% He) and xenon (content of 1.5% Xe) for pressures of 1, 2, and 3 Torr and a discharge current of 10 mA are carried out. The discharge is ignited in a tube with a radius of 1.25 cm. According to the measurements, the electron energy distribution function (EEDF) has a form close to the Maxwellian function in the low-energy region. A characteristic feature of the measured distribution functions is also a plateau in the energy range of 1-4 eV. The formation of this plateau is associated with fast electrons (4.5 eV) formed during chemionization with the participation of metastable xenon atoms. The calculations are performed within the nonstationary Boltzmann equation in the local approximation for the EEDF, taking into account the source of fast electrons. Experimental and calculated results are compared.