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Title: Laser irradiance scaling in polar direct drive implosions on the National Ignition Facility

Polar-direct-drive experiments conducted at the National Ignition Facility [E. I. Moses, Fusion Sci. Technol. 54, 361 (2008)] performed at laser irradiance between 1 and 2×1015 W/cm2 exhibit increased hard x-ray emission, decreased neutron yield, and reduced areal density as the irradiance is increased. Experimental x-ray images at the higher irradiances show x-ray emission at the equator, as well as degraded symmetry, that is not predicted in hydrodynamic simulations using flux-limited energy transport, but that appear when non-local electron transport together with a model to account for cross beam energy transfer (CBET) is utilized. The reduction in laser power for equatorial beams required in the simulations to reproduce the effects of CBET on the observed symmetry also reproduces the yield degradation consistent with experimental data.
Authors:
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  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. General Atomics, San Diego, CA (United States)
  5. Univ. of Rochester Lab. for Laser Energetics, Rochester, NY (United States)
  6. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
OSTI Identifier:
1228755
Report Number(s):
LA-UR--14-27972
Journal ID: ISSN 1070-664X; PHPAEN
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 9; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY irradiance; X-ray imaging; neutrons; experiment design; hot carriers