On the use of high-temperature, high-pressure shock waves in gases for the controll of fine particle synthesis and chemical reaction

该项目旨在论证气体中的极强冲击波用于合成极细粉末和控制化学反应的可行性。我们主要致力于通过测量与冲击波传播有关的现象来获得实现该方法所必需的基本信息。通过构造一个电容器组，利用线爆产生了非常强的冲击波。实验已经进行了不同的线材料，长度和环境气体。电测表明，距金属丝几十mm处的冲击波传播速度约为2 km/s，压力约为50 bar。在脉冲激光阴影图中，可以看到激波后区域的粒子云。利用大维尔德数玻璃的法拉第效应，实现了玻璃成核过程的时间分辨光谱。为此，又建了一个小型的快速银行。用图像增强器拍摄了几种金属丝的光谱照片，以提供颗粒合成阶段的有用信息。最后，还测试了冲击波入射到高度多孔粉末上的情况，以获得粉末中波传播的数据。

This project aims at the demonstration of the feasibility of very strong shock waves in gases for the synthesis of very fine powders and controll of chemical reaction. We have devoted mainly to obtain fundamental information necessary to realize the method by measuring the phenomea associated with shock propagation.Very strong shock waves were generated by using the wire explosion by constructing a condenser bank. Experiments have been performed with different wire material, length and ambient gas. Electrical measurement of the explosion-generated shock propagation usggests that shock speed and pressure at several tens of mm from the wire were about 2 km/s and 50 bar, respectively. The particle-like clouds in the region after the shock front was seen in the pulsed laser shadowgraph. Large amount of soot observed after each shot might be due to the nucleation process with the clouds.Time resolved spectroscopy of the same process were realized by using the Faraday effect of the glass having large Verdet number. For this purpose, another small fast bank was constructed. Spectroscopic photos for several metal wires were taken with image intensifier to give useful information on the stage of particle synthesis.Finally, shock incidence on the highly porous powders was also tested to obtain data on wave propagation in powder.