Enhancement of Laser Wakefields via a Backward Raman Amplifier

The Backward Raman Amplifier (BRA) is proposed as a possible scheme for improving laser driven plasma wakefields. One- and two-dimensional particle-in-cell code simulations with SCPIC [1] and a 3-Wave coupling model are presented and compared to demonstrate how the BRA can be applied to the laser wakefield accelerator (LWFA) in the non-relativistic regime to counteract limitations such as pump depletion, diffraction, and dephasing [2]. Simulation results show that amplification of the driving pulse is strongest in the central high amplitude portion, causing the pulse to shorten both transversely and longitudinally. This results in a reduction or alleviation of the effects of diffraction, an increase in wake amplitude and sustainability, and provides direct insight into new methods of controlling plasma wakes in LWFA and other applications. [1] K. I. Popov et al, Physical Review Letters 105, 195002 (2010) [2] E. Esarey, C. B. Schroeder, and W. P. Leemans, Rev. Mod. Phys. 81, 1229 (2009)