Charged-particle measurements of $\rho $R symmetry at shock-bang time in NIF implosions

V. GLEBOV, P. RADHA, T. SANGSTER, LLE, R. OLSON, R. LEEPER, SNL, J. KLINE, G. KYRALA, D. WILSON, LANL, J. KILKENNY, A. NIKROO, GA. -- The Wedge Range Filter (WRF) proton spectrometers were developed for OMEGA and transferred to the NIF as National Ignition Campaign (NIC) diagnostics. In tuning campaign implosions containing D and $^{3}$He gas, the WRFs are used to measure the spectrum of protons from D-$^{3}$He reactions. From the measured energy downshift of the D$^{3}$He protons, the total $\rho $R is inferred through the plasma stopping power. Data from WRFs fielded simultaneously on the pole and equator indicate low-mode polar $\rho $R asymmetries at shock flash. Significant swings in $\rho $R P2/P0 are also observed over the ignition campaign data set, attributed to low-mode x-ray drive inhomogeneity. This work was supported in part by the U.S. DOE, LLNL and LLE.