飞秒激光脉冲和液体等离子体相互作用产生的高能电子特性研究
High energy electron emission from water plasmas produced by femtosecond laser pulses
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摘要: 文章研究了单脉冲和多脉冲飞秒激光和水等离子体相互作用产生的高能电子特性,发现多脉冲激光构型可以大幅度地增强超热电子的产生和提高其温度. 实验观测到在激光偏振面内,沿与激光轴反向夹角46°的方向,对称地喷射出两束能量大于25keV的高能电子. 二维粒子模拟结果和实验符合很好. 实验和理论都表明, 这些超热电子是通过后续脉冲与前面脉冲形成的球形液滴相互作用产生的,具体机制为共振吸收.Abstract: High energy electrons emitted from water plasmas produced by a single or multiple laser pulses are investigated. The multipulse mode greatly enhances the generation and temperature of the hot electrons. Directional emission of high energy electrons over 25 keV is observed in two symmetric directions with respect to the laser axis and at 46°from the directions of the laser electric field. Two-dimensional particle-in-cell simulations reproduce well the experimental results and indicate that the acceleration mechanism of the high energy electrons is mainly due to the resonance absorption at the edge of the spherical droplets formed by the leading pulse.