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Title: Investigation of ion kinetic effects in direct-drive exploding-pusher implosions at the NIF

Measurements of yield, ion temperature, areal density (ρR), shell convergence, and bang time have been obtained in shock-driven, D{sub 2} and D{sup 3}He gas-filled “exploding-pusher” inertial confinement fusion (ICF) implosions at the National Ignition Facility to assess the impact of ion kinetic effects. These measurements probed the shock convergence phase of ICF implosions, a critical stage in hot-spot ignition experiments. The data complement previous studies of kinetic effects in shock-driven implosions. Ion temperature and fuel ρR inferred from fusion-product spectroscopy are used to estimate the ion-ion mean free path in the gas. A trend of decreasing yields relative to the predictions of 2D DRACO hydrodynamics simulations with increasing Knudsen number (the ratio of ion-ion mean free path to minimum shell radius) suggests that ion kinetic effects are increasingly impacting the hot fuel region, in general agreement with previous results. The long mean free path conditions giving rise to ion kinetic effects in the gas are often prevalent during the shock phase of both exploding pushers and ablatively driven implosions, including ignition-relevant implosions.
Authors:
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  1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
  2. Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)
Publication Date:
OSTI Identifier:
22407920
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPUTERIZED SIMULATION; CONVERGENCE; DENSITY; DEUTERIUM; HELIUM 3; HOT SPOTS; HYDRODYNAMICS; IMPLOSIONS; INERTIAL CONFINEMENT; INERTIAL FUSION DRIVERS; ION TEMPERATURE; KNUDSEN FLOW; MEAN FREE PATH; PROBES; SPECTROSCOPY; THERMONUCLEAR FUELS; THERMONUCLEAR IGNITION; US NATIONAL IGNITION FACILITY