Numerical enhancements of the microwave resonant cavity method for plasma diagnostics

Microwave resonator method is a well established and sensitive technique of plasma density measurements, especially in low pressure plasmas. The traditional Slater approximation of very small electromagnetic field perturbation is extended and corrected by a more accurate, yet relatively simple numerical model, also addressing further phenomena such as the resonator eigenmodes and the stability of the dominant mode. The presence of a discharge tube is found to be a main source of deviation from the Slater approximation. The pre-calculated numerical correction factors are directly applicable for a range of cavity and discharge tube geometries. (paper)