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Title: Convergent ablator performance measurements

Abstract

The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other convergent ablator performance parameters have been measured using a single streaked x-ray radiograph. Traditional Abel inversion of such a radiograph is ill-posed since backlighter intensity profiles and x-ray attenuation by the ablated plasma are unknown. To address this we have developed a regularization technique which allows the ablator density profile {rho}(r) and effective backlighter profile I{sub 0}(y) at each time step to be uniquely determined subject to the constraints that {rho}(r) is localized in radius space and I{sub 0}(y) is delocalized in object space. Moments of {rho}(r) then provide the time-resolved areal density, mass, and average radius (and thus velocity) of the remaining ablator material. These results are combined in the spherical rocket model to determine the ablation pressure and mass ablation rate during the implosion. The technique has been validated on simulated radiographs of implosions at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)] and implemented on experiments at the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)].

Authors:
; ; ; ; ; ;  [1];  [2]
  1. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
  2. Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)
Publication Date:
OSTI Identifier:
21421269
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 17; Journal Issue: 10; Other Information: DOI: 10.1063/1.3486536; (c) 2010 American Institute of Physics; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ABLATION; DENSITY; IMPLOSIONS; INERTIAL CONFINEMENT; PLASMA SIMULATION; CONFINEMENT; PHYSICAL PROPERTIES; PLASMA CONFINEMENT; SIMULATION

Citation Formats

Hicks, D G, Spears, B K, Braun, D G, Sorce, C M, Celliers, P M, Collins, G W, Landen, O L, and Olson, R E. Convergent ablator performance measurements. United States: N. p., 2010. Web. doi:10.1063/1.3486536.
Hicks, D G, Spears, B K, Braun, D G, Sorce, C M, Celliers, P M, Collins, G W, Landen, O L, & Olson, R E. Convergent ablator performance measurements. United States. https://doi.org/10.1063/1.3486536
Hicks, D G, Spears, B K, Braun, D G, Sorce, C M, Celliers, P M, Collins, G W, Landen, O L, and Olson, R E. 2010. "Convergent ablator performance measurements". United States. https://doi.org/10.1063/1.3486536.
@article{osti_21421269,
title = {Convergent ablator performance measurements},
author = {Hicks, D G and Spears, B K and Braun, D G and Sorce, C M and Celliers, P M and Collins, G W and Landen, O L and Olson, R E},
abstractNote = {The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other convergent ablator performance parameters have been measured using a single streaked x-ray radiograph. Traditional Abel inversion of such a radiograph is ill-posed since backlighter intensity profiles and x-ray attenuation by the ablated plasma are unknown. To address this we have developed a regularization technique which allows the ablator density profile {rho}(r) and effective backlighter profile I{sub 0}(y) at each time step to be uniquely determined subject to the constraints that {rho}(r) is localized in radius space and I{sub 0}(y) is delocalized in object space. Moments of {rho}(r) then provide the time-resolved areal density, mass, and average radius (and thus velocity) of the remaining ablator material. These results are combined in the spherical rocket model to determine the ablation pressure and mass ablation rate during the implosion. The technique has been validated on simulated radiographs of implosions at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)] and implemented on experiments at the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)].},
doi = {10.1063/1.3486536},
url = {https://www.osti.gov/biblio/21421269}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 10,
volume = 17,
place = {United States},
year = {Fri Oct 15 00:00:00 EDT 2010},
month = {Fri Oct 15 00:00:00 EDT 2010}
}