Improvement of electron beam quality in laser wakefield acceleration by a circularly-polarized laser pulse

Electron acceleration driven by laser wakefield using a laser pulse with circular polarization is studied to generate better-quality electron bunches. In order to inject electrons into the accelerating phase of the plasma wave, a density transition shaped bump is employed. Using particle-in-cell simulations, we demonstrate the influence of laser polarization on the quality of electron bunch. The simulation results (using experimentally achievable parameters) show that the electron bunch with higher peak-energy, narrow energy-spread, and low emittance can be obtained by using a laser pulse with circular polarization as compared to the usually employed linear polarization in a mm-scale length plasma. The results show the improved quality of the electron bunch generated from laser wakefield accelerations. The predicted electron bunch quality may be crucial in developing plasma-based electromagnetic radiation sources.