RESEARCH ON EXCITATION DISCHARGES FOR SHORT WAVE LENGTH LASER BY LONGITUDINAL ELECTRIC FIELD

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The purpose of this research is to investigate the possibility of lasing discharge by means of a longitudinal electric field(LE mode)in place of the transverse electric field(TE mode). The investigation was carried out for two subjects -to prove the ASE (amplified spontaneous emission)laser by the divided electrode longitudinal discharge and to study gas-puff Z pinches for producing a high temperature, uniform plasma needed for the soft X ray laser.It was proved that the N_2 laser was emitted by the longitudinal discharge using the divided electrodes. The discharges were unstable, however, and the reproducibility was poor. These difficulties were partly improved by modifying the electrode structure, increasing the applied voltage and applying the pre-ionizing discharge. It was not possible to attain so reliable and high power laser as expected. The reason resulted from having not been able to control each discharge between adjacent electrodes. A powerful pre-ionization and finding a structure to make it possible will be necessary. They are the problems to be solved hereafter. As a by-product the improved surface flashover switches that were triggered by the corona discharge and field distortion were developed. The resistivity was lower in this switch than in the previous ones, and the damage was less. It was more reliable furthermore.On the other hand the hot plasma with the electron temeperature of more than 10^7 K was produced by the gas -puff Z pinch. The inhomogeneities resulted from external conditions were substantially decreased by improving the electrode structure and controlling the injection angle of gas. The hot spots resulted from the MHD instabilities were still observed. The number of them, however, increased by the appropriate gas injection, and they were produced along the axis.