Self-consistent and precise measurement of time-dependent radiative albedo of gold based on specially symmetrical triple-cavity Hohlraum

A self-consistent and precise method to determine the time-dependent radiative albedo, i.e., the ratio of the reemission flux to the incident flux, for an indirect-drive inertial confinement fusion Hohlraum wall material is proposed. A specially designed symmetrical triple-cavity gold Hohlraum is used to create approximately constant and near-equilibrium uniform radiation with a peak temperature of 160 eV. The incident flux at the secondary cavity waist is obtained from flux balance analysis and from the shock velocity of a standard sample. The results agree well owing to the symmetrical radiation in the secondary cavity. A self-consistent and precise time-dependent radiative albedo is deduced from the reliable reemission flux and the incident flux, and the result from the shock velocity is found to have a smaller uncertainty than that from the multi-angle flux balance analysis, and also to agree well with the result of a simulation using the HYADES opacity.