Investigation of electron beam parameters in laser wakefield acceleration using skewed laser pulse and external magnetic field

Abstract

We investigate the parameters of accelerated electron bunch in laser wakefield acceleration (LWFA), when a skewed laser pulse propagates through a plasma in the presence of a transverse magnetic field. Two dimensional particle-in-cell (2D-PIC) simulations have been performed under the consideration of pulse skewness parameter (sα=τl/τt) that is defined as the ratio of leading (τl) to trailing pulse edge (τt) duration. The injected charge is estimated as 23 pC for the laser strength parameter a0=2 when sα changes from 1 to 0.45 at a laser propagation distance of 1.5 mm with 50T magnetic field. The electron beam emittance reduces about 50% when leading edge of the pulse becomes two-fold sharper (sα=0.45) with 50T magnetic field. Energy spread of accelerated electron bunch is also reduced from 18 to 6.6%. Hence, in the presence of a transverse magnetic field, the laser pulse skewness can significantly improve the quality of the accelerated electron bunch (i.e. charge, mean energy and emittance) in laser wakefield acceleration.