Dependence of stimulated Brillouin scattering on laser intensity, laser f number, and ion species in hohlraum plasmas

摘要

Stimulated Brillouin scattering has been studied in plasma conditions approaching those expected within laser-driven cavities (hohlraums) capable of driving a fusion capsule to ignition with x rays. These conditions are achieved using a gas-filled hohlraum design that was fielded at the Nova laser. As the intensity of an interaction beam (351 nm in wavelength) is increased above an onset value Ic, the measured Brillouin backscatter into the lens rises sharply and saturates. Ic decreases as the optic f number increases. The saturation level depends on the gas ion species.