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This content will become publicly available on November 6, 2018

Title: Simultaneous diagnosis of radial profiles and mix in NIF ignition-scale implosions via X-ray spectroscopy

In a National Ignition Facility implosion, hydrodynamic instabilities may cause the cold material from the imploding shell to be injected into the hot-spot (hot-spot mix), enhancing the radiative and conductive losses, which in turn may lead to a quenching of the ignition process. The bound-bound features of the spectrum emitted by high-Z ablator dopants that get mixed into the hot-spot have been previously used to infer the total amount of mixed mass; however, the typical errorbars are larger than the maximum tolerable mix. We present in this paper an improved 2D model for mix spectroscopy which can be used to retrieve information on both the amount of mixed mass and the full imploded plasma profile. By performing radiation transfer and simultaneously fitting all of the features exhibited by the spectra, we are able to constrain self-consistently the effect of the opacity of the external layers of the target on the emission, thus improving the accuracy of the inferred mixed mass. The model's predictive capabilities are first validated by fitting simulated spectra arising from fully characterized hydrodynamic simulations, and then, the model is applied to previously published experimental results, providing values of mix mass in agreement with previous estimates. Finally, wemore » show that the new self consistent procedure leads to better constrained estimates of mix and also provides insight into the sensitivity of the hot-spot spectroscopy to the spatial properties of the imploded capsule, such as the in-flight aspect ratio of the cold fuel surrounding the hotspot.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ; ORCiD logo [4] ;  [1] ;  [4] ;  [1] ; ORCiD logo [3] ;  [1]
  1. Univ. of Oxford (United Kingdom). Dept. of Physics. Clarendon Lab.
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Univ. of York (United Kingdom). Dept. of Physics
  4. Univ. of Rochester, NY (United States). Lab. for Laser Energetics
Publication Date:
Report Number(s):
LLNL-JRNL-736521
Journal ID: ISSN 1070-664X
Grant/Contract Number:
AC52-07NA27344; NA0001944; EP/L000849/1; EP/L000644/1; EP/H035877/1
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 11; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of Rochester, NY (United States); Univ. of Oxford (United Kingdom); Univ. of York (United Kingdom)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); New York State Energy Research and Development Authority (NYSERDA) (United States); Engineering and Physical Sciences Research Council (EPSRC); Royal Society (United Kingdom)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; doping; atmospheric radiation; x-ray spectroscopy; radiography; hydrodynamics; tectonophysics; electronic structure; emission spectra
OSTI Identifier:
1438689
Alternate Identifier(s):
OSTI ID: 1407434