The role of high-energy electrons in the formation of the transverse profile of high-speed ionization wave fronts in gases

A comprehensive experimental study of the spatio-temporal structure of the fronts of discrete, high-speed ionization waves (HSIW) in shielded discharge tubes filled with inert gases is carried out. It is shown that the ionization wave front at low gas pressures (below 1 Torr) has a volumetric structure, but at gas pressures above 10 Torr assumes a cylindrical form, compressed into the dielectric boundary of the discharge tube. The high-energy electrons generated at the ionization wave front have a significant impact on its structure and their energy relaxation modes. Evaluations of the energies of electrons accelerated at the HSIW front are provided along with an analysis of the influence of the energy relaxation regimes of the high-energy electrons on the structure and dynamics of the development of the ionization wave front in the shielded dielectric discharge tubes.