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A novel method to measure ion density in ICF experiments using X-ray spectroscopy of cylindrical tracers

Abstract:
The indirect drive approach to inertial confinement fusion (ICF) has undergone important advances in the past years. The improvements in temperature and density diagnostic methods are leading to more accurate measurements of the plasma conditions inside the hohlraum and therefore to more efficient experimental designs. The implementation of dot spectroscopy has proven to be a versatile approach to extracting spaceand time-dependent electron temperatures. In this method a microdot of a mid-Z material is placed inside the hohlraum and its K-shell emission spectrum is used to determine the plasma temperature. However, radiation transport of optically thick lines acting within the cylindrical dot geometry influences the outgoing spectral distribution in a manner that depends on the viewing angle. This angular dependence has recently been studied in the high energy density (HED) regime at the OMEGA laser facility, which allowed us to design and benchmark appropriate radiative transfer models that can replicate these geometric effects. By combining these models with the measurements from the dot spectroscopy experiments at the National Ignition Facility (NIF), we demonstrate here a novel technique that exploits the transport effects to obtain time-resolved measurements of the ion density of the tracer dots, without the need for additional diagnostics. We find excellent agreement between experiment and simulation, opening the possibility of using these geometric effects as a density diagnostic in future experiments.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1063/5.0012474

Authors


More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Role:
Author
ORCID:
0000-0003-3719-2352
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Role:
Author
More by this author
Institution:
University of Oxford
Role:
Author


Publisher:
AIP Publishing
Journal:
Physics of Plasmas More from this journal
Volume:
27
Issue:
2020
Article number:
112714
Publication date:
2020-11-19
Acceptance date:
2020-10-29
DOI:
ISSN:
1070-664X


Language:
English
Keywords:
Pubs id:
1140137
Local pid:
pubs:1140137
Deposit date:
2020-10-30

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