Study on Optimization of Barrier Discharge Excimer-Lamp

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In order to improve the capability of of Xe gas excimer lamps from which vacuum ultra-violet light is obtained, the characteristics and filamentation of barrier discharge plasma, and the factors which determine the light intensity and efficiency have been investigated. The main results obtained in this work are as follows.1) In aXe gas barrier plasma, the magnitude of charge concentration accumulated on the surface of barriers increased with decreasing the frequencies of power source, and the production rate of excimers increased with decreasing the rise-time of the pulse voltage applied to plasma. Filamentation which might occur by non-uniformity in a uniform volume discharges was found to be initiated by a local gas temperature rise in excimer laser discharges.2) In order to understand a relation between the laser spectroscopic signals and the plasma properties in non-equilibrium plasmas, the photon concentrations which are used for the laser diagnostics did not appreciably disturb the electron energy distribution but significantly changes the concentration of local excited levels.3) In Xe/Ne mixtures, the laser absorption and opt-galvanic signals showed that the concentration of the metastable Xe was largest in the vicinity of the cathode under DC discharge. In the case of LF (10kHz-500kHz) discharges, the concentration had two peaks in the vicinity of the ground and powered electrodes.As a conclusion it was suggested that an optimum design of excimer lamps was to utilize the sheath regions where the electron temperature was high enough to obtain a high value of excimer production rate.