Implications of differences between measured and hydro-simulated reaction histories in hydrodynamic-like implosions on OMEGA

Hong Sio

PSFC

Tuesday, February 27, 2018

5:00pm

NW17-218

PSFC Student Seminars

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.