Laser Wakefield Acceleration Experiments in the Self Modulated Regime at Titan

Picosecond laser plasma interaction has been studied as a novel source of producing betatron x-rays. In this regime, electrons are accelerated through the interplay of two mechanisms: self-modulated laser wakefield acceleration and direct laser acceleration. The experiment, conducted on the Titan laser system (1 ps and 150 Joules) at Lawrence Livermore National Lab, using electron densities of $0.5-1.5\times10^{19}cm^{-3}$, found electrons accelerated to energies of up to 250 MeV with divergence half angles on order of 10s of milliradians. Corresponding to the electron densities above, frequency shifts of laser light on order $\omega_p\sim 1.5-2\times 10^{14}$ rad/sec were measured using Raman forward scattering diagnostics.