Observations of Multiple Nuclear Reaction Histories and Fuel-Ion Species Dynamics in Shock-Driven Inertial Confinement Fusion Implosions

Abstract

Fuel-ion species dynamics in hydrodynamiclike shock-driven DT³He-filled inertial confinement fusion implosion is quantitatively assessed for the first time using simultaneously measured D³He and DT reaction histories. These reaction histories are measured with the particle x-ray temporal diagnostic, which captures the relative timing between different nuclear burns with unprecedented precision (∼10 ps). The observed 50±10 ps earlier D³He reaction history timing (relative to DT) cannot be explained by average-ion hydrodynamic simulations and is attributed to fuel-ion species separation between the D, T, and ³He ions during shock convergence and rebound. At the onset of the shock burn, inferred ³He/T fuel ratio in the burn region using the measured reaction histories is much higher as compared to the initial gas-filled ratio. As T and ³He have the same mass but different charge, these results indicate that the charge-to-mass ratio plays an important role in driving fuel-ion species separation during strong shock propagation even for these hydrodynamiclike plasmas.