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. 11. Electron beam spectra from the single-stage LWFA a#cod#x2013;b and the two-stage LWFA c#cod#x2013;h. The plasma density of the second stage is c 5 #cod#x00D7; 10 18 cm #cod#x2013;3 , d 4 #cod#x00D7; 10 18 cm #cod#x2013;3 , e 3.5 #cod#x00D7; 10 18 cm #cod#x2013;3 , f#cod#x2013;g 2.5 #cod#x00D7; 10 18 cm #cod#x2013;3 , and h 2 #cod#x00D7; 10 18 cm #cod#x2013;3 . [ 70 ]