Journal Article

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

Schmitt, M J, Leatherland, A, Gales, S, Herrmann, H W, Sepke, S M, Hammel, B A, Zylstra, A, Kim, Y H, McEvoy, A M

2016

Overview

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.

• Publisher: IOP Publishing
• Subject: Fuels / Gamma rays / Implosions / INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY / mix / NUCLEAR FUEL CYCLE AND FUEL MATERIALS / Perturbation / Physics / Thermal diffusion / Thickness