Using HT and DT gamma rays to diagnose mix in Omega capsule implosions

[摘要] Experimental evidence [1] indicates that shell material can be driven into the core of Omega capsule implosions on the same time scale as the initial convergent shock. It has been hypothesized that shock-generated temperatures at the fuel/shell interface in thin exploding pusher capsules diffusively drives shell material into the gas core between the time of shock passage and bang time. We propose a method to temporally resolve and observe the evolution of shell material into the capsule core as a function of fuel/shell interface temperature (which can be varied by varying the capsule shell thickness). Our proposed method uses a CD plastic capsule filled with 50/50 HT gas and diagnosed using gas Cherenkov detection (GCD) to temporally resolve both the HT "clean" and DT "mix" gamma ray burn histories. Simulations using Hydra [2] for an Omega CD-lined capsule with a sub-micron layer of the inside surface of the shell pre-mixed into a fraction of the gas region produce gamma reaction history profiles that are sensitive to the depth to which this material is mixed. An experiment to observe these differences as a function of capsule shell thickness is proposed to determine if interface mixing is consistent with thermal diffusion λii∼T2/Z2ρ at the gas/shell interface. Since hydrodynamic mixing from shell perturbations, such as the mounting stalk and glue, could complicate these types of capsule-averaged temporal measurements, simulations including their effects also have been performed showing minimal perturbation of the hot spot geometry.

[发布机构] Los Alamos National Laboratory, Los Alamos; MS; 87545, United States^1;Lawrence Livermore National Laboratory, 7000 East Ave, Livermore; CA; 94550, United States^2;Atomic Weapons Establishment, Aldermaston, Reading, Berkshire; RG7 4PR, United Kingdom^3

[关键词] Experimental evidence;Hydrodynamic mixing;Interface mixing;Interface temperatures;Plastic capsule;Shell materials;Shell thickness;Temporal measurements