Analysis and Application of a Parallel E-Class Amplifier as RF Plasma Source

The design and construction of a 13.56-MHz RF power amplifier has been carried out on the basis of a modified resonant LC circuit in parallel regarding to the classic E-class amplifier LC series resonant circuit; this was done in order to take advantage of the operation characteristics of the resonant capacitor as a bidirectional voltage source. Therefore, the parallel LC circuit amplifies the voltage signals which can be applied to resistive or capacitive-resistive loads without the need for an impedance matching network, conventionally used with plasma generators. The main achievement of the described instrumentation lays in its constant response under a wide interval of load impedance. This facility has been applied to the generation of steady discharges in plasma needle appliances and both parallel plate and coaxial dielectric barrier discharge (DBD) reactors. Some relevant results of the DBD sterilization of four different kinds of microorganisms are included, showing the feasibility of the technique within reduced processing times, under 80 s in all the cases.