Studies on Relaxation-Time-Difference Laser by Supersonic Nozzle Flow and the Superposition of Discharge

一种新开发的激波管不需要传统激波管所具有的隔膜就可以工作，以便分离高压区和低压区。在无隔膜式激波管中，不需要在每次实验后更换隔膜。这样，就有可能减少实验中的杂质流入。例如，在具有激波加热和超音速喷嘴流动(快膨胀)系统的CO_2-N_2情况下，即使是少量的H_2O也对粒子数反转的程度非常敏感。因此，非隔膜型激波管对于本方案中粒子数反转的详细研究是非常重要的。此外，实验的重现性和效率有望大大提高。图1显示了无隔膜激波管中的高压驱动活塞。圆柱体部分C和D填充有…比驾驶室的气压更高。由于在活塞B的中心钻了一个小针孔(ψ=1 mm)，所以在初始阶段气缸截面C和D的压力是相等的。当气体从C部分通过排气阀释放时，C部分的压力迅速下降。由于通过C和D之间的针孔的导电率很低，压力不平衡很快形成，这将导致活塞B快速向左侧移动。当D段中的气体通过侧孔流出时，D段与驾驶室之间的压力不平衡导致活塞A快速向左侧移动，从而使驾驶室中的高压气体流入从动室。因此，一种用于气动激光研究的无隔膜式激波管被开发出来。就会产生冲击波。为了实现活塞的快速运动，进行了几项改进，最终成功地实现了冲击波的传播。观察了冲击波到达时压力变化的动态行为，并用压电计测量了冲击波的速度，最终获得了10.6μm波段CO_2-N_2混合气体的气动激光振荡

A shock tube has been newly developed to be operated without a diaphragm which the conventional shock tube has in order to separate the high and low pressure regions. By this new scheme, several advantageous properties are expected to be obtained.In the non-diaphragm type shock tube, there is no necessity for replacing a diaphragm after each experiment. Thus, it will be possible to reduce influx of impurities in the experiment. For example, even a small amount of H_2O is anticipated to be quite sensitive for the extent of population inversion in CO_2-N_2 case with shock wave heating and supersonic nozzle flow (fast expansion) system. Consequently, a non-diaphragm type shock tube is very important for the detailed studies of population inversion in this scheme. In addition, the reproducibility and the efficiency of experiments may be expected to be largely improved.High pressure driven pistons in the non-diaphragm shock tube are shown in Fig.1. The cylinder sections C and D are filled w … More ith a higher pressure gas than that of the driver room. Since a small pinhole (ψ=1mm) is drilled at the center of the piston B, the pressures of cylinder sections C and D are equal at the initial stage. When the gas is released from the C part through exhaust valve, the pressure of section C quickly decreases. Because of a low conductance through the pinhole between C and D, a pressure imbalance quickly develops and this will lead the fast movement of the piston B toward left hand side. When the gas in the section D flows out through lateral holes, the pressure imbalance between the section D and the driver room causes a fast movement of the piston A to the left side, and this makes the high pressure gas in the driver room flows into the driven room. Consequently, A non-diaphragm type shock tube is being developed for the gas-dynamic laser research. a shock wave will occur. Several improvements have been carried out in order to have quick movement of pistons, and finally the shock wave propagation has been successfully obtained. The dynamic behaviors of pressure changes caused by the arrival of shock waves have been observed, and the shock wave velocity has been measured by using piezo electric gauges.Finally, the gas-dynamic laser oscillation of 10.6μm band with the CO_2-N_2 mixture has been obtained Less