On electron energy distribution functions in low-pressure magnetic multicusp hydrogen discharges

Abstract

Following the approach which was used in a previous paper for the calculation of the EEDF for an electron-beam sustained discharge in a magnetic multicusp geometry, the authors examine the influence of some physical processes such as energy sharing between free electrons issuing from ionisation and superelastic collisions associated with vibrational deexcitation. Particular attention is devoted to low-pressure conditions which are commonly used for the production of intense beams of H- ions. Even for high current values the EEDF is proved to be largely non-maxwellian. On the basis of their results the authors prove that the influence of vibrational excitation on the EEDF is weak, allowing the calculations of the EEDF without any precise knowledge of the vibrational populations.