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Investigation of iron opacity experiment plasma gradients with synthetic data analysesa)
a)Contributed paper, published as part of the Proceedings of the 19th Topical Conference on High-Temperature Plasma Diagnostics, Monterey, California, May 2012.
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View: Figures


Image of FIG. 1.

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FIG. 1.

The sample composition for (a) an Fe+Mg sample and (b) an Al+Fe+Mg sample and their synthetic transmission spectra under 10% gradient with the average T e and n e of 195 eV and 8 × 1022 cm−3. Layer numbers correspond to the subscript i in Eqs. (1) and (2).

Image of FIG. 2.

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FIG. 2.

Linear gradient analysis finds T e and n e from synthetic spectra computed for (a) the Fe+Mg sample and (b) the Al+Fe+Mg sample. The actual gradient (solid black line) falls within the error bars. Open squares with red error bars are results on the backlighter side, and filled circles with green error bars are those on the observer side. Layer numbers indicate the location in the samples (Fig. 1).

Image of FIG. 3.

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FIG. 3.

Gradient analysis results are shown for (a) the Fe+Mg sample and (b) the Al+Fe+Mg sample for different gradient levels. The inferred gradients are indicated by the conditions on the backlighter side (open squares with red error bars) and that on the observer side (filled circle with green error bars). The dashed lines indicate the true values on each side.

Image of FIG. 4.

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FIG. 4.

Analysis results (a) T e and (b) n e as a function of noise level for 10% gradient level.

Image of FIG. 5.

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FIG. 5.

Film data using the Al+Fe+Mg sample. Al and Mg lines are indicated by the labels on the film image.


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Experiments have been performed at Sandia National Laboratories Z-facility to validate ironopacity models relevant to the solar convection/radiation zone boundary. Sample conditions were measured by mixing Mg with the Fe and using Mg K-shell line transmission spectra, assuming that the plasma was uniform. We develop a spectral model that accounts for hypothetical gradients, and compute synthetic spectra to quantitatively evaluate the plasma gradient size that can be diagnosed. Two sample designs are investigated, assuming linear temperature and density gradients. First, Mg uniformly mixed with Fe enables temperature gradients greater than 10% to be detected. The second design uses Mg mixed into one side and Al mixed into the other side of the sample in an attempt to more accurately infer the sample gradient. Both temperature and density gradients as small as a few percent can be detected with this design. Experiments have successfully recorded spectra with the second design. In future research, the spectral model will be used to place bounds on gradients that exist in Z opacityexperiments.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Investigation of iron opacity experiment plasma gradients with synthetic data analysesa)