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Title: Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments

Abstract

Temporally resolved measurements of the hohlraum radiation flux asymmetry incident onto a bismuth coated surrogate capsule have been made over the first two nanoseconds of ignition relevant laser pulses. Specifically, we study the P2 asymmetry of the incoming flux as a function of cone fraction, defined as the inner-to-total laser beam power ratio, for a variety of hohlraums with different scales and gas fills. This work was performed to understand the relevance of recent experiments, conducted in new reduced-scale neopentane gas filled hohlraums, to full scale helium filled ignition targets. Experimental measurements, matched by 3D view factor calculations, are used to infer differences in symmetry, relative beam absorption, and cross beam energy transfer (CBET), employing an analytic model. Despite differences in hohlraum dimensions and gas fill, as well as in laser beam pointing and power, we find that laser absorption, CBET, and the cone fraction, at which a symmetric flux is achieved, are similar to within 25% between experiments conducted in the reduced and full scale hohlraums. This work demonstrates a close surrogacy in the dynamics during the first shock between reduced-scale and full scale implosion experiments and is an important step in enabling the increased rate of study formore » physics associated with inertial confinement fusion.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;  [1]
  1. Lawrence Livermore National Laboratory, Livermore, California, 94550 (United States)
Publication Date:
OSTI Identifier:
22489934
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 12; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 2-2-DIMETHYLPROPANE; ABSORPTION; ASYMMETRY; BISMUTH; CAPSULES; COATINGS; ENERGY TRANSFER; HELIUM; IMPLOSIONS; INERTIAL CONFINEMENT; LASER RADIATION; PHOTON BEAMS; PULSES; RADIATION FLUX; SYMMETRY; THERMONUCLEAR IGNITION

Citation Formats

Pak, A., Dewald, E. L., Landen, O. L., Milovich, J., Strozzi, D. J., Berzak Hopkins, L. F., Bradley, D. K., Divol, L., Ho, D. D., MacKinnon, A. J., Meezan, N. B., Michel, P., Moody, J. D., Moore, A. S., Schneider, M. B., Town, R. P. J., Hsing, W. W., and Edwards, M. J. Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments. United States: N. p., 2015. Web. doi:10.1063/1.4936803.
Pak, A., Dewald, E. L., Landen, O. L., Milovich, J., Strozzi, D. J., Berzak Hopkins, L. F., Bradley, D. K., Divol, L., Ho, D. D., MacKinnon, A. J., Meezan, N. B., Michel, P., Moody, J. D., Moore, A. S., Schneider, M. B., Town, R. P. J., Hsing, W. W., & Edwards, M. J. Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments. United States. doi:10.1063/1.4936803.
Pak, A., Dewald, E. L., Landen, O. L., Milovich, J., Strozzi, D. J., Berzak Hopkins, L. F., Bradley, D. K., Divol, L., Ho, D. D., MacKinnon, A. J., Meezan, N. B., Michel, P., Moody, J. D., Moore, A. S., Schneider, M. B., Town, R. P. J., Hsing, W. W., and Edwards, M. J. Tue . "Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments". United States. doi:10.1063/1.4936803.
@article{osti_22489934,
title = {Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments},
author = {Pak, A. and Dewald, E. L. and Landen, O. L. and Milovich, J. and Strozzi, D. J. and Berzak Hopkins, L. F. and Bradley, D. K. and Divol, L. and Ho, D. D. and MacKinnon, A. J. and Meezan, N. B. and Michel, P. and Moody, J. D. and Moore, A. S. and Schneider, M. B. and Town, R. P. J. and Hsing, W. W. and Edwards, M. J.},
abstractNote = {Temporally resolved measurements of the hohlraum radiation flux asymmetry incident onto a bismuth coated surrogate capsule have been made over the first two nanoseconds of ignition relevant laser pulses. Specifically, we study the P2 asymmetry of the incoming flux as a function of cone fraction, defined as the inner-to-total laser beam power ratio, for a variety of hohlraums with different scales and gas fills. This work was performed to understand the relevance of recent experiments, conducted in new reduced-scale neopentane gas filled hohlraums, to full scale helium filled ignition targets. Experimental measurements, matched by 3D view factor calculations, are used to infer differences in symmetry, relative beam absorption, and cross beam energy transfer (CBET), employing an analytic model. Despite differences in hohlraum dimensions and gas fill, as well as in laser beam pointing and power, we find that laser absorption, CBET, and the cone fraction, at which a symmetric flux is achieved, are similar to within 25% between experiments conducted in the reduced and full scale hohlraums. This work demonstrates a close surrogacy in the dynamics during the first shock between reduced-scale and full scale implosion experiments and is an important step in enabling the increased rate of study for physics associated with inertial confinement fusion.},
doi = {10.1063/1.4936803},
journal = {Physics of Plasmas},
number = 12,
volume = 22,
place = {United States},
year = {Tue Dec 15 00:00:00 EST 2015},
month = {Tue Dec 15 00:00:00 EST 2015}
}