Focusing of shock waves induced by optical breakdown in water
Focusing of shock waves induced by optical breakdown in water
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DOI：
10.1121/1.2903865
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发表时间：
2008-06-01
影响因子：
2.4
通讯作者：
Zhong, Pei
中科院分区：
文献类型：
--
作者：
Sankin, Georgy N.;Zhou, Yufeng;Zhong, Pei
实验和数值模拟研究了激光冲击波在截头椭球反射镜上的聚焦。测量了椭球反射镜第一焦点（F-1）和第二焦点（F-2）周围的压力波形和分布。用波长为1046 nm、脉宽为5 ns的掺钕钇铝石榴石激光器在F1处产生光学击穿，产生了峰值压力为2.1-5.9 MPa、脉冲半峰宽为36-65 ns的球面发散冲击波。在反射时，产生会聚冲击波，其在到达F-2时具有峰值压力为26 MPa和过零脉冲持续时间为0.1 μ s的前导压缩波，随后是峰值压力为-3.3 MPa和脉冲持续时间为0.2 μ s的拖尾拉伸波。聚焦冲击波场的-6 dB波束尺寸沿沿着和横向于冲击波传播方向为1.6 x 0.2 mm（2）。在高激光能量水平下形成细长等离子体限制了F-2处峰值压力的增加。收敛激波波形轮廓的一般特征与基于汉密尔顿模型的数值模拟定性一致。(c)2008年，美国声学学会。
The focusing of laser-generated shock waves by a truncated ellipsoidal reflector was experimentally and numerically investigated. Pressure waveform and distribution around the first (F-1) and second foci (F-2) of the ellipsoidal reflector were measured. A neodymium doped yttrium aluminum garnet laser of 1046 ran wavelength and 5 ns pulse duration was used to create an optical breakdown at F1, which generates a spherically diverging shock wave with a peak pressure of 2.1-5.9 MPa at 1.1 mm stand-off distance and a pulse width at half maximum of 36-65 ns. Upon reflection, a converging shock wave is produced which, upon arriving at F-2, has a leading compressive wave with a peak pressure of 26 MPa and a zero-crossing pulse duration of 0.1 mu s, followed by a trailing tensile wave of -3.3 MPa peak pressure and 0.2 mu s pulse duration. The -6 dB beam size of the focused shock wave field is 1.6 x 0.2 mm(2) along and transverse to the shock wave propagation direction. Formation of elongated plasmas at high laser energy levels limits the increase in the peak pressure at F-2. General features in the waveform profile of the converging shock wave are in qualitative agreement with numerical simulations based on the Hamilton model. (c) 2008 Acoustical Society of America.