A simple time-dependent analytic model of the P2 asymmetry in cylindrical hohlraums

A simple time-dependent analytic view factor model for the $P_2$ asymmetry in cylindrical hohlraums is presented. The model includes the effects of hohlraum wall motion, time-varying hohlraum wall albedo and time-varying hohlraum-to-capsule diameter. The results of the model compare well with predictions from two-dimensional radiation hydrodynamics computer simulations and with time-resolved hohlraum symmetry data obtained at the Nova laser facility [J. T. Hunt and D. R. Speck, Opt. Eng. 28, 461 (1989)] and Omega laser facility [J. M. Sources, R. L. McCrory, C. P. Verdon et al., Phys. Plasmas 3, 2108 (1996)]. The model is also extended to the more complicated but relevant case of a multiple-ring cylindrical hohlraum illumination geometry, the baseline scheme for the National Ignition Facility [J. A. Paisner, J. D. Boyes, S. A. Kumpan, and M. Sorem, ICF Quart. 5, 110 (1995)].