Collision cross sections and deposition efficiencies for argon ion excitation by relativistic electrons

Abstract

Unusual light emission has been observed in relativistic-electron-beam (REB)-produced plasmas in rare gases. In order to understand these studies of argon ion emission produced by a relativistic electron beam, the authors have generated a complete set of cross sections and deposition efficiencies for singly ionized argon experiencing collisions with relativistic electrons. Calculations of the electron impact excitation cross sections considering electrons with energies up to and including relativistic values have been made using the first Born approximation modified by Fano and the generalized oscillator formalism. Deposition efficiencies for fast electrons were generated from an integral equation based on the continuously slowing down approximation calculations of the energy apportionment for electron energies from 1 keV to 10 MeV. For most transitions the values of the efficiencies are roughly constant above a beam energy of about 1 keV, although in a few cases the efficiency continues to increase up to beam electron energies of 10 keV. Electrons ejected from inner shells contribute up to 12% of the efficiency of the transition for electrons above 10 keV.<>