Calibrated simulations of opacity experiments that reproduce the experimentally measured plasma conditions
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Prism Computational Sciences, Madison, WI (United States)
Recently, frequency-resolved iron opacity at electron temperatures of 170-200 eV and electron densities of 0.7 — 4.0 x 1022 cm-3 were measured at Sandia National Laboratories and revealed 30 - 400 % disagreement with the calculated opacities [J. E. Bailey et al, Nature 517, 56 (2015)]. The discrepancies have a high impact on astrophysics, atomic physics, and HED physics, and it is important to support our understanding of the experiments with simulations. Reliable simulations are challenging because the temporal and spatial evolution of the source radiation and the sample plasma are both complex and incompletely diagnosed. In this article we describe simulations that successfully reproduce the measured temperature and density in recent iron opacity experiments performed at the Sandia National Laboratories Z facility. The time dependent spectral irradiance at the sample is estimated using the measured time and space dependent source radiation distributions, in-situ source-to-sample distance measurements, and a 3-D view factor code. The indicated spectral irradiance is used to drive 1-D sample radiation hydrodynamics simulations. The images recorded by slit-imaged space-resolved spectrometers are modeled by solving radiation transport of the source radiation through the sample. We discovered that the same drive radiation time history successfully reproduced the measured plasma conditions for eight different opacity experiments. Simulations of the backlight radiation source absolute brightness, spectral dependence, and spatial distribution agree with measurements within the experiment uncertainties, providing further evidence for the simulation method validity. These simulation results refine our understanding of the source radiation, sample plasma heating and evolution, and image formation.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1258476
- Alternate ID(s):
- OSTI ID: 1237118; OSTI ID: 1512885
- Report Number(s):
- SAND-2015-10206J; SAND-2015-6006J; PLEEE8; 642138
- Journal Information:
- Physical Review E, Vol. 93, Issue 2; ISSN 2470-0045
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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