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Title: Assessment of ion kinetic effects in shock-driven inertial confinement fusion implosions using fusion burn imaging

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.4921935· OSTI ID:22410522
; ; ; ; ; ; ;  [1]; ; ;  [2];  [3]; ; ;  [4]; ; ; ;  [5];
  1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
  2. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
  3. Dipartimento SBAI, Università di Roma “La Sapienza” and CNISM, Via A. Scarpa 14-16, I-00161 Roma (Italy)
  4. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
  5. Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

The significance and nature of ion kinetic effects in D{sup 3}He-filled, shock-driven inertial confinement fusion implosions are assessed through measurements of fusion burn profiles. Over this series of experiments, the ratio of ion-ion mean free path to minimum shell radius (the Knudsen number, N{sub K}) was varied from 0.3 to 9 in order to probe hydrodynamic-like to strongly kinetic plasma conditions; as the Knudsen number increased, hydrodynamic models increasingly failed to match measured yields, while an empirically-tuned, first-step model of ion kinetic effects better captured the observed yield trends [Rosenberg et al., Phys. Rev. Lett. 112, 185001 (2014)]. Here, spatially resolved measurements of the fusion burn are used to examine kinetic ion transport effects in greater detail, adding an additional dimension of understanding that goes beyond zero-dimensional integrated quantities to one-dimensional profiles. In agreement with the previous findings, a comparison of measured and simulated burn profiles shows that models including ion transport effects are able to better match the experimental results. In implosions characterized by large Knudsen numbers (N{sub K} ∼ 3), the fusion burn profiles predicted by hydrodynamics simulations that exclude ion mean free path effects are peaked far from the origin, in stark disagreement with the experimentally observed profiles, which are centrally peaked. In contrast, a hydrodynamics simulation that includes a model of ion diffusion is able to qualitatively match the measured profile shapes. Therefore, ion diffusion or diffusion-like processes are identified as a plausible explanation of the observed trends, though further refinement of the models is needed for a more complete and quantitative understanding of ion kinetic effects.

OSTI ID:
22410522
Journal Information:
Physics of Plasmas, Vol. 22, Issue 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
Country of Publication:
United States
Language:
English

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Using multiple secondary fusion products to evaluate fuel ρR, electron temperature, and mix in deuterium-filled implosions at the NIF journal August 2015
Ion-kinetic simulations of D- 3 He gas-filled inertial confinement fusion target implosions with moderate to large Knudsen number journal January 2016
Observation and modeling of interspecies ion separation in inertial confinement fusion implosions via imaging x-ray spectroscopy journal March 2017
Ion species stratification within strong shocks in two-ion plasmas journal March 2018
Progress on observations of interspecies ion separation in inertial-confinement-fusion implosions via imaging x-ray spectroscopy journal June 2019
Probing ion species separation and ion thermal decoupling in shock-driven implosions using multiple nuclear reaction histories journal July 2019
Plasma kinetic effects on interfacial mix and burn rates in multispatial dimensions journal June 2019
Kinetic physics in ICF: present understanding and future directions journal April 2018
Spectral composition of thermonuclear particle and recoil nuclear emissions from laser fusion targets intended for modern ignition experiments journal June 2018
Compression and burning of a direct-driven thermonuclear target under the conditions of inhomogeneous heating by a multi-beam megajoule laser journal January 2019
Nuclear diagnostics for Inertial Confinement Fusion (ICF) plasmas journal January 2020
Deciphering the kinetic structure of multi-ion plasma shocks journal November 2017
Nuclear yield reduction in inertial confinement fusion exploding-pusher targets explained by fuel-pusher mixing through hybrid kinetic-fluid modeling journal September 2018
Observations of Multiple Nuclear Reaction Histories and Fuel-Ion Species Dynamics in Shock-Driven Inertial Confinement Fusion Implosions journal January 2019
Observation and modeling of interspecies ion separation in inertial confinement fusion implosions via imaging x-ray spectroscopy text January 2017
Deciphering the Kinetic Structure of Multi-Ion Plasma Shocks text January 2017
Ion Species Stratification Within Strong Shocks in Two-Ion Plasmas text January 2017