Control and diagnosis of temperature, density, and uniformity in x-ray heated iron/magnesium samples for opacity measurements
Control and diagnosis of temperature, density, and uniformity in x-ray heated iron/magnesium samples for opacity measurements
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DOI：
10.1063/1.4872324
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发表时间：
2014-05
期刊：
影响因子：
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通讯作者：
T. Nagayama;J. Bailey;G. Loisel;S. Hansen;G. Rochau;R. Mancini;J. Macfarlane;I. Golovkin
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文献类型：
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作者：
T. Nagayama;J. Bailey;G. Loisel;S. Hansen;G. Rochau;R. Mancini;J. Macfarlane;I. Golovkin
实验测试正在进行中，以评估太阳内部条件下模拟的铁不透明度的准确性，特别是为了更好地限制太阳丰度问题[S.巴苏和 H.M. Antia，物理报告 457, 217 (2008)]。在这里，我们描述了满足可靠不透明度实验的三个关键要求的测量：样品条件的控制、独立的样品条件诊断和样品条件均匀性的验证。不透明样品由塑料夯实的铁/镁层组成。通过改变塑料厚度，我们控制铁等离子体条件以达到 i) Te=167+/-3 eV 和 ne=(7.1+/-1.5)e21 e/cc，ii) Te=170+/-2 eV 和 ne=(2.0+/-0.2)e22 e/cc，以及 iii) Te=196+/-6 eV 和 ne=(3.8+/-0.8)e22 e/cc。 通过镁示踪 K 壳层光谱法。不透明度样品的不均匀性通过单独的实验直接测量，其中Al混合到样品面向辐射源的一侧，Mg混合到另一侧。通过铝和镁 K 壳光谱证实铁的状态在测量不确定度范围内是均匀的。这些条件适合测试太阳内部、其他恒星和高能量密度等离子体建模所需的不透明度计算。
Experimental tests are in progress to evaluate the accuracy of the modeled iron opacity at solar interior conditions, in particular to better constrain the solar abundance problem [S. Basu and H.M. Antia, Physics Reports 457, 217 (2008)]. Here we describe measurements addressing three of the key requirements for reliable opacity experiments: control of sample conditions, independent sample condition diagnostics, and verification of sample condition uniformity. The opacity samples consist of iron/magnesium layers tamped by plastic. By changing the plastic thicknesses, we have controlled the iron plasma conditions to reach i) Te=167+/-3 eV and ne=(7.1+/-1.5)e21 e/cc, ii) Te=170+/-2 eV and ne=(2.0+/-0.2)e22 e/cc, and iii) Te=196+/-6 eV and ne=(3.8+/-0.8)e22 e/cc, which were measured by magnesium tracer K-shell spectroscopy. The opacity sample non-uniformity was directly measured by a separate experiment where Al is mixed into the side of the sample facing the radiation source and Mg into the other side. The iron condition was confirmed to be uniform within their measurement uncertainties by Al and Mg K-shell spectroscopy. The conditions are suitable for testing opacity calculations needed for modeling the solar interior, other stars, and high energy density plasmas.