Bindhu C V, Harilal S S, Tillack M S, Najmabadi F, Gaeris A C
Center for Energy Research, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0438, USA.
Appl Spectrosc. 2004 Jun;58(6):719-26. doi: 10.1366/000370204872917.
The energy absorption and laser propagation characteristics of air and argon sparks at one atmosphere have been investigated. To create the sparks, 532 nm pulses from a frequency doubled Q-switched Nd : YAG laser are used. We employed 2 ns gated fast photography for studying the time evolution of the kernel at early times. Optical emission spectroscopy is used to infer temperature and density of the sparks. Significant energy absorption by the plasma is observed just above the breakdown threshold. The energy absorption and propagation in the spark indicated that argon plasma is more absorptive than air plasma. The absorption of the spark increases with laser energy, and at higher energies absorption saturation is observed. A spiky behavior is observed in the transmitted temporal profiles of lasers at higher energies and this is explained as due to the formation of a self-regulating regime.
研究了一个大气压下空气和氩气火花的能量吸收及激光传播特性。为产生火花，使用了倍频调Q开关Nd:YAG激光器的532 nm脉冲。我们采用2 ns选通快速摄影来研究早期内核的时间演化。利用发射光谱法推断火花的温度和密度。在略高于击穿阈值时观察到等离子体有显著的能量吸收。火花中的能量吸收和传播表明，氩等离子体比空气等离子体的吸收性更强。火花的吸收随激光能量增加，在较高能量下观察到吸收饱和。在较高能量下，激光的透射时间轮廓呈现出尖峰行为，这被解释为是由于形成了自调节机制。
