Picosecond interferometry and analysis of pressure fields around nanosecond microdischarge filaments that develop in deionized water
Picosecond interferometry and analysis of pressure fields around nanosecond microdischarge filaments that develop in deionized water
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DOI：
10.35848/1347-4065/ab75b6
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发表时间：
2020-03
影响因子：
1.5
通讯作者：
P. Hoffer;V. Prukner;J. Schmidt;M. Šimek
中科院分区：
文献类型：
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作者：
P. Hoffer;V. Prukner;J. Schmidt;M. Šimek
本研究利用高空间分辨率（0.75 μm）的激光干涉测量技术，研究了在去离子水中使用快速上升时间正高压脉冲（+100 kV，持续时间10 ns）在点电极上产生的纳秒放电周围形成的压力场。采用Nd:YAG激光（532 nm, 30 ps），采用Mach-Zehnder干涉仪的概念。液体折射率的变化产生了由干涉仪投射的干涉图样中条纹的偏移。高空间分辨率与超快激光源相结合，可以在放电演化的任何阶段获取干涉图像。因此，获得了独特的结果，即由于单个放电灯丝的传播而形成的特征压力场。在激波前半径为2 μm处，估计峰值压力为500 MPa；在这个早期阶段，产生的灯丝是看不见的。冲击波振幅可能与电压无关。
This study investigated pressure fields that develop around nanosecond discharges produced in deionised water by fast rise-time positive high-voltage pulses (+100 kV, duration 10 ns) on a point electrode by means of laser interferometry with high spatial resolution (0.75 μm). The concept of the Mach–Zehnder interferometer was employed using Nd:YAG laser (532 nm, 30 ps). Changes in the liquid refractive index produced a shift in the fringes in interference patterns projected by the interferometer. High spatial resolution combined with the ultrafast laser source allowed the acquisition of interferometric images at any phase of the discharge evolution. Consequently, unique results were obtained that characterised pressure fields that develop due to the propagation of a single discharge filament. The peak pressure of 500 MPa was estimated at the shock front with a radius of 2 μm; the generating filament was invisible at this early stage. The shockwave amplitudes were probably voltage independent.