Particle-in-cell simulations of laser-plasma interaction for the shock ignition scenario

Numerical simulations of the laser pulse interaction with an inhomogeneous, large size, high temperature plasma are presented. The laser pulse intensity, 10(16) W cm(-2), plasma temperature, 5 keV, and the density scale length of 300 mu m correspond to the conditions of the shock ignition scenario. It is demonstrated that after a short initial burst of backscattering, a significant part of the incident laser radiation is absorbed in the underdense plasma and the energy is transported to the dense plasma by electrons with energies 20-40 keV. The absorption mechanism is associated with a self-organized resonator and cavitation of large-amplitude plasma waves in the density range below the quarter critical density. The temporal and spectral properties of reflected light are discussed.