In the ionization injection regime of laser wakefield acceleration (LWFA), the control and optimization of electron bunches is a major concern. We address this by demonstrating the generation of tunable electron bunches in LWFA using temporally asymmetric laser pulses in the ionization injection regime. The introduction of pulse asymmetry modifies the wakefield structure, which affects the accelerating field and electron trapping in the ionization injection regime. Our 2D PIC simulations show that fast trailing edge asymmetry of the laser pulse produces narrow electron bunches with improved energies, whereas slow trailing edge asymmetry favors prolonged injection and yields broader bunches with higher charge. These results reveal that the temporal shape of the driving laser pulse serves as a control parameter for tailoring the charge, duration, and quality of the injected electron beam. This approach offers a versatile pathway for tunable electron bunch generation in LWFA without requiring changes in plasma density or gas composition. This paves the way for the development of compact, high-brightness electron sources for advanced accelerator and radiation applications.
Ravina et al. (Wed,) studied this question.