Reemission technique for symmetry measurements in Hohlraum targets containing a centered high-Z ball

A technique for measuring time-resolved drive symmetry in a laser-irradiated Hohlraum is presented. Design considerations and experimental method and results are emphasized. The experimental method involves x-ray imaging a high-Z ball placed in the center of a laser irradiated Hohlraum. We will show that the reemitted x-ray image can be measured as a function of time and that the images are directly related to the radiation flux asymmetry within the Hohlraum. Results from a series of experiments performed on the Nova laser located at Lawrence Livermore National Laboratory will be presented as well as a method for comparing with theoretical calculations. Detailed comparisons between theoretical calculations and experimental results will be given.