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无预脉冲、P极化、1016W/cm2的紫外(248nm)超短(420fs)激光以45°角辐照到靶面上,实验数据列于表1。研究结果表明,靶材料对激光吸收机制没有影响,对于较宽的紫外脉冲激光,靶的厚度对激光吸收效率影响很小,但对超热电子的空间行为有很大影响。在靶厚度在10μm以下,超热电子温度并不随厚度减小而降低,约为15keV左右,这个结果与红外超短(120fs)的有很大差异,这是由于紫外光脉宽较大,使得只有脉冲前半部分的激光被靶等离子体吸收,而脉冲后部能
No pre-pulse, P-polarized, 1016W / cm2 ultraviolet (248nm) ultra-short (420fs) laser irradiation to the target surface angle of 45 °, the experimental data are shown in Table 1. The results show that the target material has no effect on the laser absorption mechanism. For a wide range of UV pulsed laser, the thickness of the target has little effect on the laser absorption efficiency but has a great impact on the spatial behavior of the hot electron. When the target thickness is under 10μm, the temperature of the hot electron does not decrease with the decrease of the thickness, about 15keV. This result is greatly different from that of the ultra-short infrared (120fs) due to the large pulse width of UV light, Only the first half of the laser pulse is absorbed by the target plasma, while the back of the pulse can be