Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Prism Computational Sciences, Madison, Wisconsin 53711, USA.
Phys Rev E. 2017 Jun;95(6-1):063206. doi: 10.1103/PhysRevE.95.063206. Epub 2017 Jun 26.
Iron opacity calculations presently disagree with measurements at an electron temperature of ∼180-195 eV and an electron density of (2-4)×10^{22}cm^{-3}, conditions similar to those at the base of the solar convection zone. The measurements use x rays to volumetrically heat a thin iron sample that is tamped with low-Z materials. The opacity is inferred from spectrally resolved x-ray transmission measurements. Plasma self-emission, tamper attenuation, and temporal and spatial gradients can all potentially cause systematic errors in the measured opacity spectra. In this article we quantitatively evaluate these potential errors with numerical investigations. The analysis exploits computer simulations that were previously found to reproduce the experimentally measured plasma conditions. The simulations, combined with a spectral synthesis model, enable evaluations of individual and combined potential errors in order to estimate their potential effects on the opacity measurement. The results show that the errors considered here do not account for the previously observed model-data discrepancies.
目前，铁的不透明度计算结果与电子温度约为 180-195 eV 和电子密度为 (2-4)×10^{22}cm^{-3} 的测量结果不一致，这些条件类似于太阳对流区底部的条件。这些测量使用 X 射线对用低 Z 材料夯实的薄铁样品进行体积加热。不透明度是从光谱分辨的 X 射线透射测量中推断出来的。等离子体自发射、堵塞衰减以及时间和空间梯度都可能导致测量不透明度光谱中的系统误差。在本文中，我们通过数值研究定量评估了这些潜在的误差。该分析利用了先前发现可以重现实验测量等离子体条件的计算机模拟。这些模拟与光谱合成模型相结合，可以对单个和组合的潜在误差进行评估，以估计它们对不透明度测量的潜在影响。结果表明，这里考虑的误差并不能解释之前观察到的模型与数据之间的差异。
