Low power microwave conductivity of atmospheric pressure plasma

Air, He, and Ar plasmas are analyzed at different pressures between 10²-10⁵ Pa. COMSOL simulation is used to approximate the value of plasma conductivity. Electron density is calculated for a scattering time tau of about 10^-11 s, which is very close to the critical density, for which plasma frequency equals the microwave frequency. This might explain the sign change of the imaginary part of conductivity.