A SYSTEMATIC STUDY ON LASER CHARACTERISTICS OF GAS-LASER BY MEANS OF THE SHOCK TUBE

对于采用楔形喷嘴的CO2气体动力激光器，激光功率取决于距离喷嘴喉部的距离，并且存在激光功率最大的最佳距离。这种特点是由于斜激波。流动显示实验证实了斜激波的存在。进行了考虑斜激波影响的二维数值分析。在激波构型上，流动显示结果与计算结果吻合较好。小信号增益系数的实验值与计算值吻合较好。因此，斜激波的影响如下：斜激波后激光气体的平动温度升高。因此，种群反转消失，小信号增益降低。激光介质通过斜激波再加热。为了对后混合气体动力激光器进行实验研究，设计了实验装置。它由两个隔膜式激波管组成。在用这些xhock管进行后混合型气体动力激光实验时，需要同步滞止条件。传统的膜片式激波管难以同步两种滞止状态，而本实验装置能够同步两种滞止状态。用上述装置测量了小信号增益和激光功率。这一结果似乎对激波管技术是有用的。研究用于气体动力激光器的高温气体的热物理性质是十分必要的。在本研究中，作为进一步研究的第一步，用激波管测量了高温气体的热导率。

In case of employing a wedge nozzle for CO2 Gasdynamic Laser, the Laser power depends on a distance from nozzle throat and there is the optimum distance where the Laser power is the largeset. This caracteristics is because of the oblique shock wave. The existance of the oblique shock wave was confirmed by the flow visualization experiments. Two-dimentional mumelical analysis which considers the influence of the oblique shock wave was carried out. In the shock wave configuration, good agreement between the results of flow visualization and calculation was obtaind. Experimental value of small signal gain coefficient agreed well with the calculated one. Consequently, the influence of the oblique shock wave is as follows : Translational temperature of the Laser gas increases behind the oblique shock wave. Therefor, the population inversion becomes extinct and the small signal gain is decreased. The Laser medium is reheated by passing through the oblique shock wave.in order to carry out an experimental study on an after-mixing Gasdynamic Laser, experimental apparatus was designed. That was made up of two diaphragm type shock tubes. In the case of after-mixing type Gasdynamic Laser experiments by using these xhock tubes, it is necessary to synchronize the stagnation conditions. it is difficult to synchronize two stagnation conditions by using a conventional diaphragm type shock tube, however, this experimental apparatus enables to synchronize them. Small signal gains and Laser powers were measured by using the above apparatus. This result appears to be useful for the shock tube technique.It is necessary to study the themophysical properties of high temperature gases which are used for Gasdynamic Laser. In this research, as the first step of the further study, the themal conductivity of high temperature gases were measured by the shock tube.