Electron energy distributions in e-beam generated Xe and Ar plasmas

Abstract

Calculations have been performed to determine the time evolution of electron energy distributions in e‐beam generated Xe and Ar plasmas. In these calculations, we have included electron‐neutral elastic and inelastic collisions, electron‐electron collisions, and electron‐ion dissociative recombination. Our results indicate that in equilibrium the distributions can be reasonably approximated by a Maxwellian below the thresholds for inelastic electron‐neutral processes. However, above these thresholds, the inelastic processes dominate so that the high‐energy tails of the distributions are largely missing. As a result, a model which takes the distribution to be Maxwellian everywhere somewhat underestimates the average energy of the electrons or overestimates the ionization and direct‐impact excitation rates. At very early times and after the removal of the e‐beam, there can be significant departures from a Maxwellian distribution. Following removal of the e‐beam, the electrons equilibrate with the gas; however, this equilibration occurs on a time scale that is long compared to many other processes in noble‐gas eximer laser systems.