Multiphysical Study of an Atmospheric Microwave Argon Plasma Jet

In this paper, the multiphysical and frequency-dependent characterization of a microwave argon plasma jet in the GHz range is presented. Three different frequency ranges around 1.3, 2.4, and 3.5GHz are compared using electrical, geometrical, optical, and thermal analyses for different power levels between 2 and 10 W at a constant gas flow. Based on measurements using the large signal S-parameter measuring technique, the plasma base point impedance and microwave conductivity are determined via circuit and finite-element method simulations. Major changes within a small frequency interval are exhibited. Optical measurements are dependent on the geometrical dimension changes of the microwave plasma. It is shown that the geometrical dimensions are strongly dependent on frequency and applied power. These investigated dependencies of the microwave plasma on operation conditions open up new degrees of freedom to match the frequency to the application needs. A description of different applications is given based on the different areas of the measurement results.