Analytical and Numerical Simulation of a Microwave-Sustained Argon Plasma Torch at Moderate Pressures

This paper presents a 3D multiphysics model of a 20 Torr argon microwave plasma torch in a WR−187 waveguide. Coupling plasma transport, Maxwell’s equations, compressible flow and heat transfer, the simulation solves the 2.45 GHz TE10 microwave input from 10 to 50 W using nine-reaction argon chemistry. At 50 W, the results show the maximum electron density ∼ 1018m−3 in an annular pattern near the waveguide-tube junction, gas temperatures up to ∼ 1000 K, and strong plasma shielding of the electric field. The self-consistent coupling of electromagnetic fields, ionization, and heating is aligned with prior experimental and computational work, validating the approach for reactor design.