59th Annual Meeting of the APS Division of Plasma Physics
Volume 62, Number 12
Monday–Friday, October 23–27, 2017;
Milwaukee, Wisconsin
Session TI2: Direct Drive, Fast Ignition, and Kinetic Modeling
9:30 AM–12:30 PM,
Thursday, October 26, 2017
Room: 102ABC
Chair: John Kline, Los Alamos National Laboratory
Abstract ID: BAPS.2017.DPP.TI2.2
Abstract: TI2.00002 : Wavelength Detuning Cross-Beam Energy Transfer Mitigation Scheme for Direct-Drive: Modeling and Evidence from National Ignition Facility Implosions
10:00 AM–10:30 AM
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Abstract
Author:
J.A. Marozas
(Laboratory for Laser Energetics, U. of Rochester)
Cross-beam energy transfer (CBET) has been shown to significantly reduce the
laser absorption and implosion speed in direct-drive implosion experiments
on OMEGA and the National Ignition Facility (NIF). Mitigating CBET assists
in achieving ignition-relevant hot-spot pressures in deuterium--tritium
cryogenic OMEGA implosions. In addition, reducing CBET permits lower, more
hydrodynamically stable, in-flight aspect ratio ignition designs with
smaller nonuniformity growth during the acceleration phase. Detuning the
wavelengths of the crossing beams is one of several techniques under
investigation at the University of Rochester to mitigate CBET. This talk
will describe these techniques with an emphasis on wavelength detuning.
Recent experiments designed and predicted using multidimensional
hydrodynamic simulations including CBET on the NIF have exploited the
wavelength arrangement of the NIF beam geometry to demonstrate CBET
mitigation through wavelength detuning in polar-direct-drive (PDD)
implosions.\footnote{J. A. Marozas \textit{et al.}, ``First Observation of Cross-Beam
Energy Transfer Mitigation for Direct-Drive Inertial Confinement Fusion
Implosions Using Wavelength Detuning at the National Ignition Facility,''
submitted to Physical Review Letters.} Shapes and trajectories inferred from
time-resolved x-ray radiography of the imploding shell, scattered-light
spectra, and hard x-ray spectra generated by suprathermal electrons all
indicate a reduction in CBET. These results and their implications for
direct-drive ignition will be presented and discussed. In addition,
hydrodynamically scaled ignition-relevant designs for OMEGA implosions
exploiting wavelength detuning will be presented. Changes required to the
OMEGA laser to permit wavelength detuning will be discussed. Future plans
for PDD on the NIF including more-uniform implosions with CBET mitigation
will be explored. This material is based upon work supported by the
Department of Energy National Nuclear Security Administration under Award
Number DE-NA0001944.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2017.DPP.TI2.2