Title: Calibrated simulations of $Z$ opacity experiments that reproduce the experimentally measured plasma conditions

Abstract

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 plasmamore » 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.« less

Authors:

Nagayama, T. ^[1]; Bailey, J. E. ^[1]; Loisel, G. ^[1]; Rochau, G. A. ^[1]; MacFarlane, J. J. ^[2]; Golovkin, I. ^[2]

---

+ Show Author Affiliations

1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2. Prism Computational Sciences, Madison, WI (United States)

Publication Date:

Fri Feb 05 00:00:00 EST 2016

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1258476

Alternate Identifier(s):

OSTI ID: 1237118; OSTI ID: 1512885

Report Number(s):

SAND-2015-10206J; SAND-2015-6006J
Journal ID: ISSN 2470-0045; PLEEE8; 642138

Grant/Contract Number:  

AC04-94AL85000

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review E

Additional Journal Information:

Journal Volume: 93; Journal Issue: 2; Journal ID: ISSN 2470-0045

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY