Articles techniques et présentations

In this paper, we examine changes of the electric field distributions in waveguide-based axial-type microwave plasma source (MPS) during tuning procedure. The distributions strongly depend on position of the movable short, so does the wave reflection coefficient of the incident wave. A method of determining tuning characteristics of the MPS consisting in treating the MPS as a two-port network, finding its scattering matrix coefficients and then calculating the reflection coefficient from analytical expressions is proposed. The results of calculations show that the tuning characteristics depend on plasma parameters such as the electron density and on MPS dimensions such as the height of the reduced-height waveguide section. It is possible to find such a position of the movable short for which the reflected wave power is less than 10% of the incident wave power.