Fig. 1. Correlated electron momentum distributions in NSDI of He: (a) 750 nm, 0.4 PW/cm²; (b) 750 nm, 0.6 PW/cm²; (c) 750 nm, 0.8 PW/cm²; (d) 1500 nm, 0.4 PW/cm²; (e) 1500 nm, 0.6 PW/cm²; (f) 1500 nm, 0.8 PW/cm². He原子NSDI的关联电子动量分布　(a) 750 nm, 0.4 PW/cm²; (b) 750 nm, 0.6 PW/cm²; (c) 750 nm, 0.8 PW/cm²; (d) 1500 nm, 0.4 PW/cm²; (e) 1500 nm, 0.6 PW/cm²; (f) 1500 nm, 0.8 PW/cm²

Fig. 2. Proportion of each return in the total NSDI yield: (a) 750 nm; (b) 1500 nm.各次返回诱导的NSDI在总的NSDI中所占的百分比　(a) 750 nm; (b) 1500 nm

Fig. 3. Recollison distance in NSDI for (a) 750 nm and (b) 1500 nm at the laser intensities of 0.4, 0.6 and 0.8 PW/cm². NSDI事件关于碰撞距离的概率分布　(a) 750 nm; (b) 1500 nm.

Fig. 4. Correlated electron momentum distributions in NSDI of He for 750 nm at the laser intensities of 0.4 (the first row), 0.6 (the second row) and 0.8 PW/cm² (the third row). The columns from left to right correspond to return numbers of 1 to 5. 750 nm 激光脉冲驱动He原子NSDI的关联电子动量分布　(a)—(e) 0.4 PW/cm²; (f)—(j) 0.6 PW/cm²; (k)—(o) 0.8 PW/cm²; 从左到右每列对应不同返回次数诱导的NSDI事件

Fig. 5. Correlated electron momentum distributions in NSDI of He for 1500 nm at the laser intensities of 0.4 (the first row), 0.6 (the second row) and 0.8 PW/cm² (the third row). The columns from left to right correspond to return numbers of 1 to 5. 1500 nm 激光脉冲驱动He原子NSDI的关联电子动量分布　(a)—(e) 0.4 PW/cm²; (f)—(j) 0.6 PW/cm²; (k)—(o) 0.8 PW/cm²; 从左到右每列对应不同返回次数诱导的NSDI事件