ELECTRODELESS HIGH-PRESSURE MICROWAVE DISCHARGES

A one-dimensional numerical model has been developed to describe a cylindrical high-pressure mercury plasma sustained by microwave energy within a cavity applicator by solving Maxwell's equations together with the energy balance equation. The mercury line radiation has been taken into account for the energy balance by solving the radiation transfer equation for all significant wavelengths. An experimental microwave circuit for the frequency range of 2-4 GHz (S band) has been designed to guarantee stable discharge operation. Coupling efficiencies >99% into the microwave cavity can always be achieved with proper adjustments. Variation of discharge parameters leads to different types of temperature distributions including profiles with a local minimum in the axis. The temperature distributions predicted by the model are in good agreement with results from spectroscopic experiments.