Experimental Approach to Interaction Physics Challenges of the Shock Ignition Scheme Using Short Pulse Lasers

An experimental program was designed to study the most important issues of laser-plasma interaction physics in the context of the shock ignition scheme. In the new experiments presented in this Letter, a combination of kilojoule and short laser pulses was used to study the laser-plasma coupling at high laser intensities for a large range of electron densities and plasma profiles. We find that the backscatter is dominated by stimulated Brillouin scattering with stimulated Raman scattering staying at a limited level. This is in agreement with past experiments using long pulses but laser intensities limited to 2×10¹⁵ W/cm², or short pulses with intensities up to 5×10¹⁶ W/cm² as well as with 2D particle-in-cell simulations.