Microwave N2–Ar plasma torch. I. Modeling

The spatial structure of a microwave plasma torch driven by an azimuthally symmetric surface wave operating in a N2–Ar mixture at atmospheric pressure is investigated. A two-dimensional (2D) self-consistent theoretical model is developed to investigate the entire spatial structure of the source, including the discharge zone, sustained by the field of the surface TM00 mode, and the postdischarge plasma. Maxwell’s equations, the rate balance equations for the most important excited species—vibrationally and electronically excited states, ions and nitrogen atoms N(S4)—and the Boltzmann equation for electrons are consistently solved. Model calculations of the 2D spatial distributions of species of interest such as charged particles (electrons and positive ions), N2(Χ Σ1g+,v) vibrationally excited molecules, N2(A Σ3u+) metastable molecules, and N(S4) ground state atoms are presented and discussed.