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

新研制的一种激波管没有传统的激波管的隔膜，以分离高、低压区。通过这种新方案，有望获得一些有利的性质。在非膜片式激波管中，每次实验后无需更换膜片。这样，就有可能减少实验中杂质的流入。例如，在激波加热和超音速喷嘴流动（快速膨胀）系统中，即使是少量的H_2O也对CO_2-N_2的人口反转程度相当敏感。因此，非隔膜型激波管对于该方案中人口反转的详细研究是非常重要的。此外，实验的可重复性和效率有望大大提高。非隔膜激波管内高压驱动活塞如图1所示。气缸C段和D段充满了比驾驶室更高压力的气体。由于在活塞B的中心钻了一个小针孔（ψ=1mm），气缸C和D段的压力在初始阶段是相等的。当气体通过排气阀从C段释放出来时，C段的压力迅速降低。由于通过针孔C和D之间的低电导，压力不平衡迅速发展，这将导致活塞B向左侧快速运动。当D段的气体通过侧孔流出时，D段与驱动室之间的压力不平衡导致活塞a向左侧快速运动，这使得驱动室的高压气体流入被驱动室。为此，研制了一种用于气体动力激光器研究的非隔膜式激波管。会产生冲击波。为了使活塞运动迅速，对活塞进行了若干改进，最终成功地获得了激波的传播。观察了激波到达后压力变化的动态特性，并利用压电计测量了激波速度。最后，在CO_2-N_2混合物中获得了10.6μm波段的气体动力学激光振荡

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