Plasma ignition system

摘要

The system for ignition of a plasma for cathode sputtering is characterised by means (4) serving for generation of charge carriers (15). With use of an electric potential applied between the gas to be ignited as a plasma and the means (4), these charge carriers are accelerated in the direction of the plasma space (2). As a result, the gas introduced into the plasma space is impact-ionised and ignited as a plasma discharge by the charge carriers. Preferably the means (4) for generation of charge carriers (15) include at least one electrical conductor (6) heatable by current to a glow temperature, so that electrons from the conductor surface are thermally emitted in the direction of the plasma space (2). The conductor (6) preferably takes the form of a tungsten wire. Before ignition of a plasma discharge the wire (6) heated to its glow temperature has a potential within a range from -15 V to -25 V, with the corresponding emission current lying within a range of 1.0-1.8 mA. In the presence of a plasma the potential of the wire is within a range from +15 V to +25 V, with the corresponding emission current lying within a range of 1.4-2.2 mA. The potential and/or the emission current are measurable during burning of the plasma, and are foreseen for control the latter.