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首次利用一台亚音速小型连续波化学氧碘激光器的探测光源。用放大法直接测量超音速化学氧碘激光器的小信号增益系数,测得了小信号增益系数随时间和气流方向的变化。 相似文献
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描述了利用脉冲光解碘原子激光器作为探测激光器测量连续波氧碘化学激光器小信号增益的方法与装置,给出了增益的测量结果,对实验结果和误差作了简单讨论。 相似文献
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氧碘化学激光器是近年来国际上竞相研究的一种高能激光器.概述了氧碘化学激光器的基本原理、阐明了提高O_2(~1△)化学发生器的效率是提高氧碘化学激光器性能的关键;展望了氧碘化学激光器可能的应用前景,指出工业应用或许是氧碘化学激光器近、中期应用的重要方面;简单介绍了中国科学院大连化学物理研究所有关氧碘化学激光方面的研究工作. 相似文献
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描述了在过剩压驱动下金刚石晶种外延生过程中,大量伴生的石墨再结晶现象。再结晶石墨抑制了金刚石的自发成核;它们分布于合成腔触媒金属的低温区,结晶数量多,晶粒片状分层,尺寸大,但出现乱层晶体结构;同时产生一定数量的无定形碳。分析认为,这与长时间的低过剩压驱动,触媒金属内有足够的碳源供给,并具备在高温高压下石墨充分结晶但又达不到完全石墨化条件有关。还讨论了在低过剩压驱动下,促进金刚石晶体外延生长的碳源可能是活化的碳原子,而不是具有乱层结构特征的再结晶石墨。 相似文献
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H. KOOKL. MONGEAU 《Journal of sound and vibration》2002,251(5):823-846
Subsonic flows over Helmholtz resonators often cause strong periodic pressure fluctuations inside the resonators over a range of outer flow velocities. The flow-excitation mechanism is known to be governed by both the shedding of discrete vortices within the shear layer over the orifice and the acoustic response of the cavity. This self-sustained oscillation phenomenon is often analyzed by using a feedback loop model where the flow excitation and the acoustic response of the resonator are approximately modelled as a forward gain function and as a backward gain function respectively. In the present work, a similar approach was followed and a new forward gain function was derived based on the concept of “vortex sound” to model the flow excitation. The formulation combined this forward gain function with a backward gain function from previous work, within the framework of the feedback loop analysis. The approximate method allowed the frequency and the relative amplitude of the cavity pressure fluctuations to be predicted for a range of flow velocities. In addition, the extended Nyquist stability criterion was used to estimate the onset and the termination velocities of the first two modes of the shear layer flow oscillations. Experimental data were obtained using a rigid-walled cavity in a low-speed wind tunnel. The results showed that the model predictions were in reasonably good agreement with the experimental data. 相似文献
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用单能慢正电子束,测量了不同氧分压下生长的La0.7Sr0.3MnO3外延膜的S参数与入射正电子能量E的关系.结果发现La0.7Sr0.3MnO3外延膜中S参数与氧分压是非单调变化的;这与沉积氧分压的两种作用相关联的.在氧分压较高的LSMO薄膜中, 空位浓度的增加主要是由沉积原子(离子)与氧原子碰撞几率增大,使其缺乏足够的动能去填补空位引起的;在低氧分压的LSMO薄膜中, 空位浓度的增大则主要是提供成膜所需要的氧原子缺乏,从而导致氧空位及其相关缺陷增加. 相似文献
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