Electron acceleration by laser produced wake field: Pulse shape effect

Analytical expressions are obtained for the longitudinal field (wake field: Ex), density perturbations (ne′) and the potential (ϕ  ) behind a laser pulse propagating in a plasma with the pulse duration of the electron plasma period. A feasibility study on the wake field is carried out with Gaussian-like (GL) pulse, rectangular–triangular (RT) pulse and rectangular–Gaussian (RG) pulse considering one-dimensional weakly nonlinear theory (ne′/n0≪1), and the maximum energy gain acquired by an electron is calculated for all these three types of the laser pulse shapes. A comparative study infers that the RT pulse yields the best results: In its case maximum electron energy gain is 33.5 MeV for a 30 fs pulse duration whereas in case of GL (RG) pulse of the same duration the gain is 28.6 (28.8)MeV at the laser frequency of 1.6 PHz and the intensity of 3.0 × 1018 W/m2. The field of the wake and hence the energy gain get enhanced for the higher laser frequency, larger pulse duration and higher laser intensity for all types of the pulses.