IONIZATION RATE IN THE PRESENCE OF RUNAWAY ELECTRONS

The role of a fast electron population, produced by the strong electri c held driving the axial current in a capillary discharge, can be esse ntial in order to justify the appreciable concentration of highly char ged C ions (C5+, C6+) as observed in many experiments with low electro n temperature. Under the assumption that a quasistationary state is es tablished during the discharge, the runaway electron distribution func tion is determined analytically for Z(eff) > 1, following the approxim ated method developed by Lebedev [A. N. Lebedev, Sov. Phys. JETP 21, 9 31 (1965)]. The strong enhancement of the ionization rate, due to the presence of an electron tail in the energy range of the ionization pot ential, is then demonstrated. (C) 1997 American Institute of Physics.