59th Annual Meeting of the APS Division of Plasma Physics
Volume 62, Number 12
Monday–Friday, October 23–27, 2017;
Milwaukee, Wisconsin
Session BI2: Ablators, Instabilities, and Asymmetries
9:30 AM–12:30 PM,
Monday, October 23, 2017
Room: 102ABC
Chair: Russell Follett, University of Rochester
Abstract ID: BAPS.2017.DPP.BI2.6
Abstract: BI2.00006 : A near one-dimensional 2-shock indirectly driven implosion at convergence ratio \textasciitilde 30
12:00 PM–12:30 PM
Preview Abstract
Abstract
Author:
Steve MacLaren
(Lawrence Livermore National Laboratory)
Inertial confinement fusion implosions at the National Ignition Facility,
while successfully demonstrating self-heating due to alpha-particle
deposition, have fallen short of the performance predicted by
one-dimensional multi-physics implosion simulations.~ The current
understanding, based on simulations as well as experimental evidence,
suggests that the principle reason for the disagreement is a breeching of
the cold fuel assembly at stagnation which would otherwise completely
confine the hot spot.~ 3-D simulations indicate a combination of low-mode
symmetry swings and ablation-front hydrodynamic instability seeded by
engineering features such as the capsule tent and fill tube lead to
localized thinning and perforation of the stagnated fuel, resulting in a
loss of hot spot pressure and energy.~ We describe a short series of
experiments on the NIF designed specifically to avoid these issues in order
to understand if, once they are removed, a suspended-fuel-layer
deuterium-tritium implosion can achieve 1-D simulated performance.~ The
particular implosion system combines a thick capsule shell with an elevated
initial ablation temperature to minimize the ablation front perturbations
from the engineering features, and incorporates a large ratio of
hohlraum-to-capsule radius as a means to permit a higher degree of control
over implosion symmetry.~ The resulting implosion at a convergence ratio of
\textasciitilde 30 was not perfectly spherically symmetric as observed by
both neutron and time-resolved x-ray imaging diagnostics.~ However, the
stagnation observables match closely the performance predicted by 1D
simulations, including, when some hot spot motion is accounted for, the
apparent ion temperature. We present this result along with the design for
an upcoming 2-shock experiment to test whether this level of agreement with
the 1D model can be achieved in the self-heating regime.
This work was performed under the auspices of the Lawrence Livermore
National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2017.DPP.BI2.6