Cavity ignition was achieved in a supersonic combustor by laser-induced gas breakdown (LIGB) and laser ablation (LA). High-speed photography and schlieren imaging were employed to characterize the ignition processes. schlieren imaging was also applied to visualize LIGB and LA in quiescent air. The input energy was approximately 200 mJ. The distance between the focal point of the convex lens and the target plate ( d ) varied from 10 mm above the target plate ( d = 10 mm) to 5 mm below the target plate ( d = −5 mm). The experiments performed in quiescent air indicated that the plasma of LA ( d = −5 mm) was relatively small. Compared to LIGB, the expansion of the hot plume resulting from LA was less significant because the plate prevented the formation of the third lobe. The primary shock wave of LA propagated faster than that of LIGB because of high pressure ratio between the plasma and the ambient air. In the supersonic combustor with d = 5 or 10 mm,...

中文翻译：

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超声波燃烧器中激光诱导的气体击穿点火和激光烧蚀点火的比较研究

在超音速燃烧室中，通过激光诱导的气体击穿（LIGB）和激光烧蚀（LA）实现腔点火。高速摄影和schlieren成像用于表征点火过程。schlieren成像还用于观察静态空气中的LIGB和LA。输入能量约为200 mJ。凸透镜的焦点和目标板（d）之间的距离从目标板上方的10 mm（d = 10 mm）到目标板下方的5 mm（d = -5 mm）变化。在静态空气中进行的实验表明，LA的等离子体（d = -5 mm）相对较小。与LIGB相比，由LA引起的热羽流的膨胀不太显着，因为该板阻止了第三叶的形成。由于等离子体与周围空气之间的高压比，洛杉矶的主要冲击波传播的速度比LIGB快。在d = 5或10 mm的超音速燃烧器中，...