PLASMA GENERATOR IGNITION CIRCUIT

摘要

The present invention relates to ignition circuitry for a plasma generator. A discharge is created by application of a high frequency or high voltage dc ignition pulse between an electrode (2a) and a first nozzle (4a). Following ignition, the discharge is redirected to a second nozzle (4b) for the purpose of moving the plasma flow from the ignition zone into the zone of application to the workpiece. The present invention is directed to plasma ignition circuitry for improving this performance. Positive thermal coefficient ("PTC") resistance is shown to be useful in reliably and reproducibly switching the arc. Alternative embodiments of the present invention relate to switching the plasma from a first nozzle (4a) to a second nozzle (4b) then sequentially to additional nozzles (5a, 5b) downstream in the flow of plasma gas in which PTC resistance is used to reliably a reproducibly effect the switching.