Observation of multiple mechanisms for stimulating ion waves in ignition scale plasmas

The laser and plasma conditions expected in ignition experiments using indirect drive inertial confinement have been studied experimentally. It has been shown that there are at least three ways in which ion waves can be stimulated in these plasmas and have a significant effect on the energy balance and distribution in the target. First ion waves can be stimulated by a single laser beam by the process of stimulated Brillouin scattering (SBS) in which an ion acoustic and a scattered electromagnetic wave grow from noise. Second, in a plasma where more than one beam intersects, ion waves can be excited at the “beat” frequency and wave number of the intersecting beams, causing the sidescatter instability to be seeded, and substantial energy to be transferred between the beams [R. K. Kirkwood et al., Phys. Rev. Lett. 76, 2065 (1996)]. And third, ion waves may be stimulated by the decay of electron plasma waves produced by stimulated Raman scattering (SRS), thereby inhibiting the SRS process [R. K. Kirkwood et al., Phys. Rev. Lett. 77, 2706 (1996)].