210 / 2023-04-15 21:04:31

Precise measurement of radiative albedo for high-Z hohlraum wall materials in inertial confinement fusion

Inertial confinement fusion; radiative opacity; radiative albedo

Radiative albedo, referring to the ratio of reemission flux to incident flux and depending on the radiative opacity of materials, will affect the energy coupling and driving symmetry in the indirect-driven inertial confinement fusion. Therefore, it is of great significance to carry out the precise experimental measurement of radiative albedo for further understand of the high Z materials opacity mode and the hohlraum energetics of indirect-driven inertial confinement fusion. The difficulty of precise measurement of radiative albedo lies in the accurate characterization of incident flux, which is a physical quantity that cannot be directly diagnosed. Compared with the traditional power balance method, this report proposes to introduce the measurement of some other related physical quantities to constrain and give a more credible incident flux. In the experiment, a special-design three-cavity hohlraum is used to form a uniform and nearly balanced radiative source at the waist of the secondary cavity. The incident flux at the waist of the secondary cavity is given by the measurement of the shock velocity and reemission flux of Al/quartz sample, and then the radiative albedo can be obtained with the precise diagnosis of reemission flux in the same ring. The experimental results show that the precision of the incident flux with related physical constraints is significantly improved compared with that given by the power balance method, and thus the precise measurement of radiative albedo is realized. The experimental results of radiative albedo for uranium are in good agreement with the simulated results.