Study of Beam Energy Saturation in Laser Wake Field Accelerators

Summary form only given. Saturation of electron beam energy has been observed experimentally in a laser wakefield accelerator [C. -T. Hsieh et al., Phys. Rev. Lett. 96, 095001 (2006)]. In the study, a two dimensional particle-in-cell simulation was performed to ascertain the physical reason for the energy saturation. Numerical results show that faster laser energy dissipation induced by transverse self-modulation of the laser pulse stops the electron beam to enter the deceleration phase, which is principally responsible for the beam energy saturation. The effect of the plasma density and laser intensity on the mechanism of energy saturation was also studied and will be presented in the paper.