Fig. 3: The statistical results of electron beam energy and charge under various delays between the two laser beams, with 5 shots for each case.
From: Demonstration of scissor-cross ionization injection in laser wakefield accelerators

a The statistical results of electron beam energy and charge under various delays between the two laser beams, with 5 shots for each case. Positive means the TL is before the DL. And the error bars represent the standard deviation of the 5 shots. b Evolution of energy spectrum as the pulse width and energy of the TL changes, while the delay is set to 0. The results show the transition from conventional ionization injection to scissor-cross ionization injection.