Optimization of Drive Uniformity in NIF Polar-Drive Implosions Using Gated X-Ray Self-Emission Images

Gated x-ray self-emission images have been obtained in ``exploding-pusher,'' polar-drive, diagnostics commissioning experiments\footnote{A. M. Cok, R. S. Craxton, and P. W. McKenty, Phys. Plasmas \textbf{15}, 082705 (2008).} on the NIF. They show a difference in drive between the pole and equator that serves as a diagnostic of drive uniformity. Modeling of the shell trajectories using the 2-D hydrodynamics code \textit{SAGE}\footnote{R. S. Craxton and R. L. McCrory, J. Appl. Phys. \textbf{56}, 108 (1984).} indicates that the difference between the pole and equator may result from deviations between the modeled and actual on-target phase-plate profiles. The sensitivity of the implosion uniformity to these profiles and to other parameters such as defocus and repointing has been explored with the goal of finding improved polar-drive--irradiation designs. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.