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Title: Polar-direct-drive experiments on the National Ignition Facility

To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive–specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beam geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D2 gas were imploded with total drive energies ranging from ~500-750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 x 1014 to 1.2 x 1015 W/cm2. Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport andmore » cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.« less
Authors:
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  1. Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299, USA
  2. Lawrence Livermore National Laboratory, Livermore, California 94550, USA
  3. U. S. Naval Research Laboratory, Washington, DC 20375, USA
  4. General Atomics, San Diego, California 92121, USA
  5. Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
Publication Date:
OSTI Identifier:
1249141
Report Number(s):
LLNL-JRNL--664443
Journal ID: ISSN 1070-664X; PHPAEN
DOE Contract Number:
AC52-07NA27344
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 5
Publisher:
American Institute of Physics (AIP)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 70 PLASMA PHYSICS AND FUSION