Polar-direct-drive experiments on the National Ignition Facility
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- Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States); High Energy Density Physics Division, Plasma Science and Fusion Center, Massachusetts Institute of Technology
- Lab. for Laser Energetics, University of Rochester, Rochester, NY (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- U. S. Naval Research Lab., Washington, DC (United States)
- General Atomics, San Diego, CA (United States)
- MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)
- U. S. Naval Research Lab., Washington, DC 20375, (United States)
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 to 750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 10¹⁴ to 1.2 10¹⁵W/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 and 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.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Massachusetts Institute of Technology, Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE; USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC52-07NA27344; NA0001857; NA0001944
- OSTI ID:
- 1182632
- Alternate ID(s):
- OSTI ID: 1228221
OSTI ID: 22410404
OSTI ID: 1249141
- Report Number(s):
- LLNL-JRNL--664443
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 22; ISSN PHPAEN; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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