Evidence of non-Maxwellian ion velocity distributions in spherical shock-driven implosions.

Mannion, O M; Taitano, W T; Appelbe, B D; Crilly, A J; Forrest, C J; Glebov, V Yu; Knauer, J P; McKenty, P W et al. · Phys Rev E · 2023

basic_science · Level V

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Abstract

The ion velocity distribution functions of thermonuclear plasmas generated by spherical laser direct drive implosions are studied using deuterium-tritium (DT) and deuterium-deuterium (DD) fusion neutron energy spectrum measurements. A hydrodynamic Maxwellian plasma model accurately describes measurements made from lower temperature (<10 keV), hydrodynamiclike plasmas, but is insufficient to describe measurements made from higher temperature more kineticlike plasmas. The high temperature measurements are more consistent with Vlasov-Fokker-Planck (VFP) simulation results which predict the presence of a bimodal plasma ion velocity distribution near peak neutron production. These measurements provide direct experimental evidence of non-Maxwellian ion velocity distributions in spherical shock driven implosions and provide useful data for benchmarking kinetic VFP simulations.