MAXWELL AND NON-MAXWELL BEHAVIOR OF ELECTRON-ENERGY DISTRIBUTION FUNCTION UNDER EXPANDING PLASMA-JET CONDITIONS - THE ROLE OF ELECTRON-ELECTRON, ELECTRON-ION, AND SUPERELASTIC ELECTRONIC COLLISIONS UNDER STATIONARY AND TIME-DEPENDENT CONDITIONS

A stationary and a time-dependent Boltzmann equation including elastic , inelastic, and superelastic terms has been solved for conditions typ ically met in expanding the Ar-H, plasma jet, i.e., for large ionizati on degrees and large concentrations of electronically excited states. The results show that the stationary electron-energy distribution func tions (EEDFs) in the presence of electron-electron and electron-ion (e -i) Coulomb collisions evolve to the bi-Maxwellian distribution functi on in which the lower temperature is determined by e-i collisions, and the higher one by superelastic electronic collisions. On the other ha nd, the time-dependent EEDF clearly shows long plateaus generated by s uperelastic electronic collisions for times comparable to the expansio n ones.