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Title: A “polar contact” tent for reduced perturbation and improved performance of NIF ignition capsules

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.5032121· OSTI ID:1765299

In indirectly driven Inertial Confinement Fusion implosions conducted on the National Ignition Facility (NIF), the imploding capsule is supported in a laser-heated radiation enclosure (called a “hohlraum”) by a pair of very thin (~15–45 nm) plastic films (referred to as a “tent”). Even though the thickness of these tents is a small fraction of that of the spherical capsule ablator (~165 μm), both numerical simulations as well as experiments indicate that this capsule support mechanism results in a large areal density (ρR) perturbation on the capsule surface at the contact point where the tent departs from the capsule. As a result, during deceleration of the deuterium-tritium (DT) fuel layer, a jet of the dense ablator material penetrates and cools the fuel hot spot, significantly degrading the neutron yield (resulting in only ~10%–20% of the unperturbed 1-D yield). In this article, we present a hypothesis and supporting design simulations of a new “polar contact” tent support system, which reduces the contact area between the tent and the capsule and results in a significant improvement in the capsule performance. Simulations predict a ~70% increase in neutron yield over that for an implosion with a traditional tent support. Overall, an initial demonstration experiment was conducted on the NIF and produced highest ever recorded primary DT neutron yield among all layered DT implosions with plastic ablators on the NIF, though more experiments are needed to comprehensively study the effect of the polar tent on implosion performance.

Research Organization:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC52-07NA27344; NA0001808
OSTI ID:
1765299
Alternate ID(s):
OSTI ID: 1466077
Report Number(s):
LLNL-JRNL-743472; 898422; TRN: US2206235
Journal Information:
Physics of Plasmas, Vol. 25, Issue 8; ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 14 works
Citation information provided by
Web of Science

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Cited By (5)

Three-dimensional modeling and hydrodynamic scaling of National Ignition Facility implosions journal May 2019
Robustness to hydrodynamic instabilities in indirectly driven layered capsule implosions journal January 2019
Stimulated backscatter of laser light from BigFoot hohlraums on the National Ignition Facility journal January 2019
Review of hydrodynamic instability experiments in inertially confined fusion implosions on National Ignition Facility journal October 2019
Progress of indirect drive inertial confinement fusion in the United States journal July 2019

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