Possible excitation and ionisation processes in a "collisionless" alkalineplasma

We report on an investigation in the magnetised alkaline plasma of a single -ended Q machine where the current-voltage characteristic of the cold endpl ate showed some new nonlinear features, which could be due to fundamental i on processes. The most interesting of these features were sudden jumps of t he electron saturation current which were partly accompanied by hysteresis. Besides that, the characteristic showed a smooth type of hysteresis that w as due to a temporary covering of the cold plate by alkaline metal from the plasma. The current jumps could be an indication that the well known nonli near potential structures that can appear in the plasma column when an elec tron current is drawn through it, are initiated by excitation and ionisatio n interactions of accelerated electrons with alkaline vapour present in the plasma column. (C) 1999 Elsevier Science B.V.