PERTURBATION THEORETICAL-ANALYSIS AND ITS APPLICATION FOR TM010-MODE MICROWAVE CAVITY OF A GAS-LASER

An analytical expression and a perturbation formula for the cavity res onant frequency dependence of plasma are derived for the cylindrical T M010-microwave plasma cavity. A comparison between the exact and the a pproximate solution shows that the perturbation theory can be used acc urately to analyze the perturbation effect on the cavity resonant freq uency caused by microwave plasma in low pressure microwave excited gas lasers. A new method is proposed to prevent detuning of the cavity by the perturbation of the plasma and glass tube, so that a uniform and steady-state microwave plasma is successfully formed and a stable lase r output power is also obtained. The electron density and the microwav e dielectric constant of a tube shell can be measured by the perturbat ion approach. (C) 1997 American Institute of Physics.