Title: The physics of long- and intermediate-wavelength asymmetries of the hot spot: Compression hydrodynamics and energetics

Abstract

To achieve ignition with inertial confinement fusion (ICF), it is important to under- stand the effect of asymmetries on the hydrodynamics and energetics of the compres- sion. This paper describes a theoretical model for the compression of distorted hot spots, and quantitative estimates using hydrodynamic simulations. The asymmetries are categorized into low (Ι < 6) and intermediate (Ι < A < 40) modes by comparison of the wavelength with the thermal-diffusion scale length. Long-wavelength modes introduce substantial nonradial motion, whereas intermediate-wavelength modes in- volve more cooling by thermal ablation. We discover that for distorted hot spots, the measured neutron-averaged properties can be very different from the real hydro- dynamic conditions. This is because mass ablation driven my thermal conduction introduces flows in the Rayleigh–Taylor bubbles, this results in pressure variation, in addition to temperature variation between the bubbles and the neutron-producing region (~1 keV for intermediate modes). The differences are less pronounced for long-wavelength asymmetries since the bubbles are relatively hot and sustain fusion reactions. The yield degradation$$-$$ with respect to the symmetric$$-$$ results primarily from a reduction in the hot-spot pressure for low modes and from a reduction in burn volume for intermediate modes. It is shown that the degradation in internal energy of the hot-spot is equivalent for both categories, and is equal to the total residual energy in the shell including the bubbles. This quantity is correlated with the shell residual kinetic energy for low-modes, and includes the kinetic energy in the bubbles for mid-modes.

Authors:

Bose, A.  ^[1];

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Betti, R. ^[2]; Shvarts, D. ^[3]; Woo, K. M. ^[2]

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+ Show Author Affiliations

1. Univ. of Rochester, Rochester, NY (United States); Univ. of Michigan, Ann Arbor, MI (United States)
2. Univ. of Rochester, Rochester, NY (United States)
3. Univ. of Michigan, Ann Arbor, MI (United States); NRCN, Beer Sheva (Israel)

Publication Date:

2017-10-03

Research Org.:

Univ. of Rochester, NY (United States). Lab. for Laser Energetics

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

Contributing Org.:

Laboratory for Laser Energetics, University of Rochester

OSTI Identifier:

1405332

Alternate Identifier(s):

OSTI ID: 1396067

Report Number(s):

2016-260, 1358
Journal ID: ISSN 1070-664X; 2016-260, 2316, 1358; TRN: US1703252

Grant/Contract Number:  

NA0001944; FC02-04ER54789; B614207

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 24; Journal Issue: 10; Journal ID: ISSN 1070-664X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY