Longitudinal voltage distribution in transverse rf discharge waveguide lasers

Abstract

The longitudinal variation in the voltage across a waveguide channel, excited by a transverse radio-frequency discharge has been analyzed in terms of simple transmission line theory. It is shown that the voltage variation follows a cosine curve for the waveguide structure in the absence of a discharge, and that this behavior is only slightly modified when a discharge is running. The voltage may exhibit variations of 30% for cases where the relevant waveguide length is only one tenth of the effective rf wavelength. However, it is shown that this variation may be reduced to below 5%, by the use of multiple feed points or by appropriate inductive termination of the line. Experimental results are in good agreement with theoretical predictions.