Power Supply for Plasma Torches Based on a Class-E Amplifier Configuration

A new RF power supply intended for low-power plasma torches is presented. It is based on a class-E amplifier, modified on the principle of a parallel LC resonant circuit, and is used here to supply the so-called 'plasma needle'. The latter is matched with a shunt inductor, and both are connected in parallel to the resonant capacitor C. This configuration is particularly useful for the control of stable discharge characteristics, for example, to resist naturally occurring variations in the load impedance, by providing the high voltage necessary to ignite and maintain the plasma. The overall system has been tested at atmospheric pressure by producing glow discharges in flows of helium and argon. We present early results that describe the device's characteristics.