High-precision room temperature Fe opacity measurements at 1000-2000eV photon energies

IF 1.6 3区物理与天体物理 Q3 PHYSICS, FLUIDS & PLASMAS

High Energy Density Physics Pub Date : 2023-12-01 DOI:10.1016/j.hedp.2023.101064

Malia L. Kao , Guillaume P. Loisel , James E. Bailey , Patrick W. Lake , Paul D. Gard , Gregory A. Rochau , George R. Burns , William R. Wampler , Haibo Huang , Michael N. Weir

{"title":"High-precision room temperature Fe opacity measurements at 1000-2000eV photon energies","authors":"Malia L. Kao , Guillaume P. Loisel , James E. Bailey , Patrick W. Lake , Paul D. Gard , Gregory A. Rochau , George R. Burns , William R. Wampler , Haibo Huang , Michael N. Weir","doi":"10.1016/j.hedp.2023.101064","DOIUrl":null,"url":null,"abstract":"<div><p>Prior measurements of room temperature (cold) Fe opacity have errors as high as <em>±</em>10 % and a spread in values that exceeds the uncertainties. These data, along with current cold opacity databases, were used for comparison with experimental solar Fe opacity. The solar Fe opacity is expected to be lower than cold Fe opacity in the <em>∼</em>1500–2000 eV photon energy range. However, results from this comparison contradicted this assumption and prompted an investigation of the precision and accuracy of cold Fe opacity measurements. Cold Fe opacity is determined here with high precision using transmission measurements of Fe foils at three characteristic line energies in the soft X-ray range (1000–2000 eV). The present opacities are determined with ≲1 % overall uncertainties. This is achieved through precise measurements of transmission and areal density which are related to opacity by the Beer-Lambert Law. Transmission is measured with overall individual uncertainties of ≲1 % and is obtained through simultaneous measurements of attenuated and unattenuated spectra using an X-ray source and a Bragg crystal spectrometer. The required areal density is indepen-dently measured using two different techniques: Rutherford Backscattering Spectroscopy and a recently-developed technique using calibrated cold absorption in the 3–17 keV range. The final areal density used in the opacity determination is an average between both methods. The measured opacity at 1188 eV is in agreement with current opacity databases but is higher by around 5–10 % at the highest photon energy (1924 eV) and lower by around 2–4 % at the lowest photon energy (1012 eV). A caveat is that opacity accuracy is linearly dependent on the areal density. We performed the first direct comparison between the two areal density methods which revealed a 7–11 % discrepancy. If one of the methods is proven correct in future studies, it may impact the opacity accuracy reported here since we use the average of the two methods. This result affects the solar Fe opacity measurements as they also rely on the accuracy of these areal density measurement techniques.</p></div>","PeriodicalId":49267,"journal":{"name":"High Energy Density Physics","volume":"49 ","pages":"Article 101064"},"PeriodicalIF":1.6000,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1574181823000307/pdfft?md5=985ad748bad3faeb094a9e63ef90556d&pid=1-s2.0-S1574181823000307-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"High Energy Density Physics","FirstCategoryId":"101","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1574181823000307","RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"PHYSICS, FLUIDS & PLASMAS","Score":null,"Total":0}

引用次数: 0

Abstract

Prior measurements of room temperature (cold) Fe opacity have errors as high as ±10 % and a spread in values that exceeds the uncertainties. These data, along with current cold opacity databases, were used for comparison with experimental solar Fe opacity. The solar Fe opacity is expected to be lower than cold Fe opacity in the ∼1500–2000 eV photon energy range. However, results from this comparison contradicted this assumption and prompted an investigation of the precision and accuracy of cold Fe opacity measurements. Cold Fe opacity is determined here with high precision using transmission measurements of Fe foils at three characteristic line energies in the soft X-ray range (1000–2000 eV). The present opacities are determined with ≲1 % overall uncertainties. This is achieved through precise measurements of transmission and areal density which are related to opacity by the Beer-Lambert Law. Transmission is measured with overall individual uncertainties of ≲1 % and is obtained through simultaneous measurements of attenuated and unattenuated spectra using an X-ray source and a Bragg crystal spectrometer. The required areal density is indepen-dently measured using two different techniques: Rutherford Backscattering Spectroscopy and a recently-developed technique using calibrated cold absorption in the 3–17 keV range. The final areal density used in the opacity determination is an average between both methods. The measured opacity at 1188 eV is in agreement with current opacity databases but is higher by around 5–10 % at the highest photon energy (1924 eV) and lower by around 2–4 % at the lowest photon energy (1012 eV). A caveat is that opacity accuracy is linearly dependent on the areal density. We performed the first direct comparison between the two areal density methods which revealed a 7–11 % discrepancy. If one of the methods is proven correct in future studies, it may impact the opacity accuracy reported here since we use the average of the two methods. This result affects the solar Fe opacity measurements as they also rely on the accuracy of these areal density measurement techniques.

查看原文本刊更多论文

在1000-2000eV光子能量下的高精度室温铁不透明度测量

先前对室温(冷)铁不透明度的测量误差高达±10%，其值的分布超出了不确定度。这些数据，连同目前的冷不透明度数据库，被用来与实验太阳铁不透明度进行比较。在~ 1500-2000 eV光子能量范围内，太阳铁不透明度预计低于冷铁不透明度。然而，这一比较的结果与这一假设相矛盾，并促使了对冷铁不透明度测量的精度和准确性的研究。在软x射线范围内(1000-2000 eV)，利用铁箔的三个特征线能量的透射测量，高精度地确定了冷铁的不透明度。目前的不透明度是由总体不确定度≤1%确定的。这是通过精确测量透射率和面密度来实现的，这与比尔-朗伯定律的不透明度有关。透射率的测量总体不确定度为< 1%，并通过使用x射线源和布拉格晶体光谱仪同时测量衰减和未衰减光谱得到。所需的面密度是使用两种不同的技术独立测量的:卢瑟福后向散射光谱和最近开发的一种技术，使用3-17 keV范围内的校准冷吸收。在不透明度测定中使用的最终面密度是两种方法之间的平均值。在1188 eV下测量的不透明度与目前的不透明度数据库一致，但在最高光子能量(1924 eV)下，不透明度提高了约5 - 10%，在最低光子能量(1012 eV)下，不透明度降低了约2 - 4%。需要注意的是，不透明度精度是线性依赖于面密度的。我们进行了两种面密度方法之间的第一次直接比较，结果显示了7 - 11%的差异。如果其中一种方法在未来的研究中被证明是正确的，它可能会影响这里报告的不透明度准确性，因为我们使用的是两种方法的平均值。这一结果影响了太阳铁不透明度的测量，因为它们也依赖于这些面密度测量技术的准确性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

High Energy Density Physics PHYSICS, FLUIDS & PLASMAS-

CiteScore

4.20

自引率

6.20%

发文量

审稿时长

6-12 weeks

期刊介绍： High Energy Density Physics is an international journal covering original experimental and related theoretical work studying the physics of matter and radiation under extreme conditions. ''High energy density'' is understood to be an energy density exceeding about 1011 J/m3. The editors and the publisher are committed to provide this fast-growing community with a dedicated high quality channel to distribute their original findings. Papers suitable for publication in this journal cover topics in both the warm and hot dense matter regimes, such as laboratory studies relevant to non-LTE kinetics at extreme conditions, planetary interiors, astrophysical phenomena, inertial fusion and includes studies of, for example, material properties and both stable and unstable hydrodynamics. Developments in associated theoretical areas, for example the modelling of strongly coupled, partially degenerate and relativistic plasmas, are also covered.