Laser Plasma Instability (LPI) Driven Light Scattering Measurements with 44 beam-lines of Nike KrF Laser$^*$

With short wavelength (248 $nm$), large bandwidth ($\sim1$ $THz$), and ISI beam smoothing, Nike KrF laser provides unique opportunities of LPI research for direct-drive inertial confinement fusion. Previous experiments at intensities $(10^{15}\sim10^{16} W/cm^2)$ exceeded two-plasmon decay (TPD) instability threshold using 12 beam-lines of Nike laser.$^{a,b}$ For further experiments to study LPI excitation in bigger plasma volumes, 44 Nike main beams have been used to produce plasmas with total laser energies up to 1 kJ of $\sim$350 psec FWHM pulses. This talk will present results of the recent LPI experiment focusing on light emission data in spectral ranges relevant to the Raman (SRS) and TPD instabilities. The primary diagnostics were time-resolved spectrometers with an absolute-intensity-calibrated photodiode array in $(0.4\sim0.8)\omega_0$ and a streak camera near $0.5\omega_0$. Blackbody temperature and expansion speed measurements of the plasmas were also made. The experiment was conducted at laser intensities of $(1\sim4)\times10^{15}$ $W/cm^{2}$ on solid planar CH targets. $^a$ J. L. Weaver, et al, NO4.14, APS DPP (2008) $^b$ J. Oh, et al, NO4.15, APS DPP (2008) * Work supported by DoE/NNSA and performed at Naval Research Laboratory.