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| 飞秒激光诱导的空气等离子体冲击波探究 |
| Investigation of air plasma shock waves induced by femtosecond laser |
| 投稿时间：2022-11-08 |
| DOI：10.3969/j.issn.1005-5630.2023.002.009 |
| 中文关键词: 超快时间分辨成像 涡旋滤波 空气等离子体 冲击波 |
| 英文关键词:ultrafast time-resolved vortex filter air plasma shock wave |
| 基金项目:国家自然科学基金（11904232，12034013）；上海市教委创新计划项目（2017-01-07-00-07-E00007） |
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| 中文摘要: |
| 一定强度的飞秒激光聚焦于空气能生成空气等离子体并诱导生成冲击波。为了观察该冲击波传播特性，引入了超快时间分辨涡旋滤波成像技术，并对观测到的冲击波动力学过程进行了分析。实验探测到泵浦能量为1.5 mJ的飞秒激光经过透镜聚焦到空气中产生等离子体空气冲击波，分析了在3~15 μs时间段冲击波的动态演化过程。结果表明，飞秒激光等离子体空气冲击波在传输时以不对称的球形形状向外扩散，且沿着激光传播方向的传播速度与背着激光传播方向的传播速度不同，分别为372 m/s和341 m/s。这一观察结果与传统的点爆炸模型的对称情形不同，尝试对该不对称动力学过程进行了合理解释。 |
| 英文摘要: |
| With a certain intensity, a femtosecond laser focusing in the air will generate an air plasma and induce a shock wave. In order to study the propagation process of the shock wave, an ultrafast time-resolved vortex filtering imaging technique is introduced in this paper, and the observed dynamic process of the shock wave is analyzed. The shock wave from air plasma was observed when pumped by a 1.5 mJ femtosecond laser focused into the air through a lens, and the dynamic evolution of the shock wave in the period from 3-15 microseconds was analyzed. The results show that the femtosecond laser plasma air shock wave diffuses outwards in an asymmetrical spherical shape, and the propagation velocity is different along the laser propagation direction and behind the laser propagation direction, which are 372 m/s and 341 m/s, respectively. This observation is different from the traditional point explosion model, namely the symmetric case. We give a reasonable explanation for this asymmetric dynamic process. |
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