Controlling Microwave Energy Deposition Using Active Plasma Elements for Material Processing Applications

Abstract This work is motivated by the need to modulate microwave beam propagation, phase, shape, and direction using an array of plasma elements. Tailoring microwave beams in this fashion will enable new material processing capabilities such as induced localized heating. An initial process example consists of a cylindrical plasma element inserted into a waveguide between a microwave radiation source and a material of interest. In order to establish the feasibility of the proposed process, an accurate model of an argon mercury plasma including plasma-microwave coupling was developed and described herein. Both microwave plasma heating and magnetic plasma couplings are considered. The required computational framework was implemented within the COMSOL Multiphysics finite element solver. The model is first used to investigate a 2D geometry, before being extended to a 3D geometry. The obtained solutions of the relevant partial differential equations and the associated predictions increased the understanding of the interplay between plasma and electromagnetic properties under consideration in the model. Model implementation confirms that a plasma element can be used to modulate incident microwave radiation, thereby shaping the transmitted beam. The framework also enables analysis of beam shaping techniques under consideration for material processing of ceramics. For ceramic processing, beam shaping techniques are being used to direct microwave radiation to predictable, localized areas in order to sinter the dielectric powders under consideration.