Holger Hinkel

Evaluation of electron trajectories in an arc discharge

Abstract Calculations of electron trajectories in the field configuration of the Freeman ion source are presented for various operating conditions. The results show that in this model the electrons emitted from the filament reach the positive arc chamber wall only under special operating conditions. Normally they travel in pseudo-cycloids undirectionally along the filament rod. Therefore, the probability of ionization of neutral gas atoms by electrons is increased near the positive end of the filament resulting in a preferential sputter erosion of this end.