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为了探索超热电子的输运过程,在100TW掺钛蓝宝石飞秒激光器上利用光学CCD相机和OMA光学多道分析仪,分别在靶背表面法线方向测量了光发射空间分布图案和光谱.实验测量结果显示,光发射空间分布图案呈圆盘状,在圆盘中明亮而强的光信号呈局部化分布,该现象表明,超热电子在输运的过程中存在成丝效应,引起严重的不稳定性;光发射光谱在3倍频和3/2倍频附近出现尖峰,分别是3次谐波和3/2次谐波,这一现象归因于超热电子束在传输的过程中产生的微束团而引起的相干渡越辐射(CTR);光发射光强随靶厚度的增加而减小.
In order to explore the transport process of superheated electrons, an optical CCD camera and an OMA optical multi-channel analyzer were used to measure the spatial distribution pattern and spectrum of light emission on the 100TW Ti: sapphire femtosecond laser. The measurement results show that the light emission spatial distribution pattern is disk-shaped, and the bright and strong light signals in the disk are localized. This phenomenon indicates that the superheated electrons have a filament-forming effect during transport and cause serious Instability; light emission spectrum in the 3 octave and 3/2 octave near the peak, respectively, the third harmonic and 3/2 harmonics, a phenomenon attributed to the hot electron beam in the transmission process (CTR). The intensity of light emission decreases with the increase of target thickness.