Ultraviolet Thomson Scattering from Direct-Drive Coronal Plasmas

Ultraviolet ($\lambda_{4\omega} =$ 263 nm) Thomson scattering (TS) was used to probe ion-acoustic waves (IAW's) and electron plasma waves (EPW's) from direct-drive coronal plasmas. Fifty-nine drive beams ($\lambda_{3\omega} =$ 351 nm) illuminate a spherical target with a radius of $\sim $860 $\mu $m. Advances in the ultraviolet (UV) TS diagnostic at the Omega Laser Facility provide the ability to detect deep UV photons ($\sim $190 nm) and allow access to scattered light from EPW's propagating near the 3$\omega $ quarter-critical surface ($\sim $2.5 $\times $ 10$^{\mathrm{21}}$ cm$^{-3})$. A series of experiments studied the effects of ablator materials on coronal plasma conditions. Electron temperatures and densities were measured from 150 $\mu $m to 400 $\mu $m from the initial target surface. Standard CH shells were compared to three-layered shells consisting of Si doped CH, Si, and Be. Early analysis indicates that these multilayered targets have less hot-electron energy as a result of higher electron temperature in the coronal plasma. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.