Laser-Induced Flourescences due to the Stark-Forbidden and the Electric Quadrupole Transitions in a Discharge Plasma

本研究的目的是详细地观察空心阴极放电中与斯塔克禁止跃迁和电四极跃迁相关的激光诱导荧光，并利用激光诱导荧光观察发展新的鞘内电场分布诊断方法。我们的主要结果如下：1.与共振相关的荧光的偏振，用激光诱导荧光法观测了平面平行空心阴极放电中的Stark禁戒跃迁和电四极跃迁。建立了碰撞-辐射模型来研究等离子体中碰撞过程对荧光的影响。2.根据测量的Stark禁禁和四极跃迁的荧光强度比，更准确地确定了阴极暗空间中的电场分布。3.还发展了一种新的方法，仅通过测量等离子体中应引起的荧光的偏振来确定等离子体中的电场分布黑暗空间中禁止史塔克的传输和四极传输。目前等离子体的测量下限估计约为10V/cm。作为未来的计划，将开发一种程序来修正相当密集的等离子体中的带电粒子产生的微场的影响，并将利用三重能级系统进行研究以扩展这一测量。

The purpose of this research is to observe in detail the laser-induced fluorescence associated with the Stark-forbidden and the electric quatrupole transitions in a hollow cathode discharge and to develop new diagnostics for electric field distribution in the sheath with applications of the laser-induced fluorescence observation. Our main results are as follows :1.Polarization of the fluorescences associated with the resonance, the Stark-forbidden and the electric quadrupole transitions from the Hel 2^1S state were observed in a plane parallel hollow cathode discharge by using laser-induced fluorescence method.A collisional-radiative model was developed to investigate effect of the collisional processes in the plasma on the fluorescences.2.The electric field distribution in the cathode dark space was determined more accurately than in our previous experiments from measured intensity ratio of the fluorescence due to the Stark forbidden to that due to the quadrupole transitions.3.Another new method was also developed to determine the electric field distribution in plasmas from measurement of only the polarization of the fluorescence which is due to both the Stark-forbidden and the quadrupole trnasitions in the dark space. The lower limit of the measurementfor the present plasma was estimated to be about 10 V/cm.4.As a future plan, a procedure will be developed to correct the effect of the charged-particle-produced microfield in rather dense plasmas, and also investigation using the triplet level system will be performed to extend this measurement.