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Title: Sensitivity of NIF-scale backlit thin shell implosions to hohlraum symmetry in the foot of the ignition drive pulse

Abstract

A necessary condition for igniting indirectly-driven inertial confinement fusion (ICF) spherical capsules on the National Ignition Facility (NIF) is controlling drive flux asymmetry to the 1% level time-integrated over the pulse and with < 10%/ns swings during the pulse [J. D. Lindl et al., 'The Physics Basis for Ignition using Indirect Drive Targets on the National Ignition Facility', Physics of Plasmas 11, 339 (2003)]. While drive symmetry during the first 2 ns of the pulse can be inferred by using the re-emission pattern from a surrogate high Z sphere [E. Dewald et al. to be published in Rev. Sci. Inst.] and symmetry during the last 5 ns inferred from the shape of fully imploded capsules [A. Hauer, N. Delamater, D. Ress et al. Rev. Sci. Instrum. 66, 672-7 (1995)], the midportion ({approx} 2-10 ns) has been shown to be amenable to detection by the in-flight shape of x-ray backlit thin shell capsules [Pollaine et. al., Physics of Plasmas 8 2357 (2001)]. In this paper, we present sensitivity studies conducted on the University of Rochester's OMEGA laser of the thin shell symmetry measurement technique at near NIF-scale for two candidate capsule ablator materials, Ge-doped CH and Cu-doped Be. These experiments usemore » both point and area backlighting to cast 4.7 keV radiographs of thin 1.4 mm initial-diameter Ge-doped CH and Cu-doped Be shells when converged a factor of {approx} 0.5 x in radius. Distortions in the position of the transmission limb of the shells resulting from drive asymmetries are measured to an accuracy of a few {micro}ms, meeting requirements. The promising results to date allow us to compare measured and predicted distortions and by inference drive asymmetries for the first 4 asymmetry modes as a function of hohlraum illumination conditions.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
965968
Report Number(s):
LLNL-JRNL-406419
Journal ID: ISSN 1070-664X; PHPAEN; TRN: US0904008
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas, vol. 16, no. 1, January 6, 2009, pp. 012702
Additional Journal Information:
Journal Volume: 16; Journal Issue: 1; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; ACCURACY; ASYMMETRY; DETECTION; IGNITION; ILLUMINANCE; IMAGES; IMPLOSIONS; INERTIAL CONFINEMENT; LASERS; PHYSICS; SENSITIVITY; SHAPE; SYMMETRY; TARGETS; US NATIONAL IGNITION FACILITY

Citation Formats

Kirkwood, R K, Milovich, J, Bradley, D K, Schmitt, M, Goldman, S R, Kalantar, D H, Meeker, D, Jones, O S, Pollaine, S M, Amendt, P A, Dewald, E, Edwards, J, Landen, O L, and Nikroo, A. Sensitivity of NIF-scale backlit thin shell implosions to hohlraum symmetry in the foot of the ignition drive pulse. United States: N. p., 2008. Web.
Kirkwood, R K, Milovich, J, Bradley, D K, Schmitt, M, Goldman, S R, Kalantar, D H, Meeker, D, Jones, O S, Pollaine, S M, Amendt, P A, Dewald, E, Edwards, J, Landen, O L, & Nikroo, A. Sensitivity of NIF-scale backlit thin shell implosions to hohlraum symmetry in the foot of the ignition drive pulse. United States.
Kirkwood, R K, Milovich, J, Bradley, D K, Schmitt, M, Goldman, S R, Kalantar, D H, Meeker, D, Jones, O S, Pollaine, S M, Amendt, P A, Dewald, E, Edwards, J, Landen, O L, and Nikroo, A. Mon . "Sensitivity of NIF-scale backlit thin shell implosions to hohlraum symmetry in the foot of the ignition drive pulse". United States. https://www.osti.gov/servlets/purl/965968.
@article{osti_965968,
title = {Sensitivity of NIF-scale backlit thin shell implosions to hohlraum symmetry in the foot of the ignition drive pulse},
author = {Kirkwood, R K and Milovich, J and Bradley, D K and Schmitt, M and Goldman, S R and Kalantar, D H and Meeker, D and Jones, O S and Pollaine, S M and Amendt, P A and Dewald, E and Edwards, J and Landen, O L and Nikroo, A},
abstractNote = {A necessary condition for igniting indirectly-driven inertial confinement fusion (ICF) spherical capsules on the National Ignition Facility (NIF) is controlling drive flux asymmetry to the 1% level time-integrated over the pulse and with < 10%/ns swings during the pulse [J. D. Lindl et al., 'The Physics Basis for Ignition using Indirect Drive Targets on the National Ignition Facility', Physics of Plasmas 11, 339 (2003)]. While drive symmetry during the first 2 ns of the pulse can be inferred by using the re-emission pattern from a surrogate high Z sphere [E. Dewald et al. to be published in Rev. Sci. Inst.] and symmetry during the last 5 ns inferred from the shape of fully imploded capsules [A. Hauer, N. Delamater, D. Ress et al. Rev. Sci. Instrum. 66, 672-7 (1995)], the midportion ({approx} 2-10 ns) has been shown to be amenable to detection by the in-flight shape of x-ray backlit thin shell capsules [Pollaine et. al., Physics of Plasmas 8 2357 (2001)]. In this paper, we present sensitivity studies conducted on the University of Rochester's OMEGA laser of the thin shell symmetry measurement technique at near NIF-scale for two candidate capsule ablator materials, Ge-doped CH and Cu-doped Be. These experiments use both point and area backlighting to cast 4.7 keV radiographs of thin 1.4 mm initial-diameter Ge-doped CH and Cu-doped Be shells when converged a factor of {approx} 0.5 x in radius. Distortions in the position of the transmission limb of the shells resulting from drive asymmetries are measured to an accuracy of a few {micro}ms, meeting requirements. The promising results to date allow us to compare measured and predicted distortions and by inference drive asymmetries for the first 4 asymmetry modes as a function of hohlraum illumination conditions.},
doi = {},
journal = {Physics of Plasmas, vol. 16, no. 1, January 6, 2009, pp. 012702},
issn = {1070-664X},
number = 1,
volume = 16,
place = {United States},
year = {2008},
month = {7}
}