Calculation of electromagnetic wave characteristics in a waveguide with plasma

Methods of quasi-static approximation and rigorous calculations of the phase constant variation of an electromagnetic wave in a rectangular waveguide with gas-discharge plasma in dielectric tubes disposed along the longitudinal axis of the waveguide are considered. It is shown that, for negative values of the plasma permittivity, there are qualitative and quantitative discrepancies between phase constant dependences on the radii of dielectric tubes calculated by these two methods.