Developments in laser wakefield accelerators: From single-stage to two-stage*
Li Wen-Tao, Wang Wen-Tao†, Liu Jian-Sheng‡, Wang Cheng, Zhang Zhi-Jun, Qi Rong, Yu Chang-Hai, Li Ru-Xin, Xu Zhi-Zhan
Fig. 3. Energy spectra of the electron beams when the laser intensity is a, d 6 #cod#x00D7; 10 18 W#cod#x00B7;cm #cod#x2013;2 , b, e 7.9 #cod#x00D7; 10 18 W#cod#x00B7;cm #cod#x2013;2 , and c, f 9 #cod#x00D7; 10 18 W#cod#x00B7;cm #cod#x2013;2 . [ 50 ]