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

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 themore » 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.« less
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [2]
  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:
Report Number(s):
2016-260, 1358
Journal ID: ISSN 1070-664X; 2016-260, 2316, 1358; TRN: US1703252
Grant/Contract Number:
NA0001944; FC02-04ER54789; B614207
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)
Research Org:
Univ. of Rochester, Rochester, NY (United States). Lab. for Laser Energetics
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Contributing Orgs:
Laboratory for Laser Energetics, University of Rochester
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1405332
Alternate Identifier(s):
OSTI ID: 1396067

Bose, A., Betti, R., Shvarts, D., and Woo, K. M.. The physics of long- and intermediate-wavelength asymmetries of the hot spot: Compression hydrodynamics and energetics. United States: N. p., Web. doi:10.1063/1.4995250.
Bose, A., Betti, R., Shvarts, D., & Woo, K. M.. The physics of long- and intermediate-wavelength asymmetries of the hot spot: Compression hydrodynamics and energetics. United States. doi:10.1063/1.4995250.
Bose, A., Betti, R., Shvarts, D., and Woo, K. M.. 2017. "The physics of long- and intermediate-wavelength asymmetries of the hot spot: Compression hydrodynamics and energetics". United States. doi:10.1063/1.4995250. https://www.osti.gov/servlets/purl/1405332.
@article{osti_1405332,
title = {The physics of long- and intermediate-wavelength asymmetries of the hot spot: Compression hydrodynamics and energetics},
author = {Bose, A. and Betti, R. and Shvarts, D. and Woo, K. M.},
abstractNote = {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.},
doi = {10.1063/1.4995250},
journal = {Physics of Plasmas},
number = 10,
volume = 24,
place = {United States},
year = {2017},
month = {10}
}

Works referenced in this record:

Crossed-beam energy transfer in direct-drive implosions
journal, May 2012
  • Igumenshchev, I. V.; Seka, W.; Edgell, D. H.
  • Physics of Plasmas, Vol. 19, Issue 5, Article No. 056314
  • DOI: 10.1063/1.4718594

Direct-drive laser fusion: Status and prospects
journal, May 1998
  • Bodner, Stephen E.; Colombant, Denis G.; Gardner, John H.
  • Physics of Plasmas, Vol. 5, Issue 5, p. 1901-1918
  • DOI: 10.1063/1.872861