Tuesday, February 27, 2018
During the last few years, an increasing number of experiments have shown that kinetic and multi-ion-fluid effects do impact the performance of an ICF implosion. Observations include: increasing yield degradation as the implosion becomes more kinetic; thermal decoupling between ion species; anomalous yield scaling for different fuel mixtures; ion diffusion; and fuel stratification. The common theme in these experiments is that the results are based on time-integrated nuclear observables that are affected by an accumulation of effects throughout the implosion, which complicate the interpretation of the data. A natural extension of these studies is therefore to conduct time-resolved measurements of multiple nuclear-burn histories to explore the dynamics of kinetic/multi-ion effects in the fuel and their impact on the implosion performance. This was accomplished through simultaneous, high-precision measurements of the relative timing of the onset, bang time and duration of DD, D3He, DT and T3He burn histories from DT3He gas-filled implosions using the Particle X-ray Temporal Diagnostic (PXTD) on OMEGA. Temperature effects alone cannot explain the observed differences in the reaction histories. Inferred 3He /T fuel ratio in the burn region using D3He / DT yield ratio shows rapidly changing fuel composition in the burn region throughout shock burn. The measured differences between the reaction histories are contrasted with average-ion-fluid hydrodynamic simulations, as well as kinetic-ion simulations using LSP. This work is supported in part by the U.S. DOE, LLNL, LLE, and NNSA SSGF.