Electron dynamics and kinetics during the formation of a virtual cathode in different media

Results are presented from the first systematic investigation of how various factors in material media influence electron kinetics during the formation of a virtual cathode in an overcritical-current electron beam. A study is made of such factors as the viscous frictional force acting on the electrons in the medium, the dielectric constant of the medium, and ionization processes induced by the electrons in the medium. The dynamics of formation of a virtual cathode and the kinetics of the so-called metastable electrons in the cathode are considered.