飞秒激光-金属薄膜靶相互作用中靶前后超热电子能谱的比较

采用电子谱仪测量了飞秒激光-金属薄膜靶相互作用中靶前和靶后产生的超热电子能谱.结果显示：靶前超热电子能谱的峰出现在约430 keV处，靶后超热电子能谱的峰出现在约175 keV处；靶前超热电子的有效温度分别为218 keV和425 keV，靶后超热电子能谱出现“软化”现象，其有效温度分别为96 keV和347 keV.靶前和靶后超热电子能谱明显不同是由于超热电子输运穿越过密等离子体和冷材料的靶，并在靶后建立Debye鞘，鞘电场使靶后超热电子能谱峰向低能端移动，鞘电场和自生磁场导致靶后超热电子能谱产生“软化”，估算出的鞘电场小于激光电场.

A comparison of energy distribution of hot electrons from the front and the rear sides of targets during the interaction of femtosecond laser with foil targets

The energy distribution of hot electrons from the front and the rear sides of targets have been measured during the interaction of femtosecond laser with the foil target. The results show that the peaks of energy spectrum of hot electrons from the front and the rear sides of targets are located at 430 keV and 175 keV, respectively. Fitted with Maxwell distribution, the temperatures of hot electrons from the front of targets are 218 keV and 425 keV. Obviously, the energy spectrum of hot electrons from the rear of targets is “softened”, which is due to Debye sheath electric field and self-magnetic field produced by hot electrons transported in the target, and has temperatures of 96 keV and 347 keV, which are lower than those from the front of targets.