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The effects of surface roughness on specular diagnostics in shocked experiments

Review of Scientific Instruments

Grant, Sean C.; Ao, Tommy A.

Many shock experiments, whether impact, laser, or magnetically driven, use reflected optical light from shocked samples to diagnose their material properties. Specifically, optical velocimetry diagnostics, which do not require absolute power measurements, are regularly used to obtain equation-of-state information of materials. However, new diagnostics will be necessary to expand the realm of measured material properties, and many useful diagnostic techniques do require absolute measurements. Thus, it is important to understand what happens at the reflective surface of shock experiments, and the effect scattering has on the light collection of optical probes. To this end, we present results from experiments done to observe the behavior of a reflected beam from a specular coating on an optical window during shock impact. We find that the specular condition of the coating is adversely affected by the shock front, but this can be mitigated by minimizing roughness on the surface preceding the coating.

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TYPE Journal Article YEAR 2019
ScopusOSTIDOI

Development of Dynamic Ellipsometry for Measurements or Iron Conductivity at Earth's Core Conditions

Grant, Sean C.; Ao, Tommy A.; Davis, Jean-Paul D.; Dolan, Daniel H.; Seagle, Christopher T.; Lin, Jung-Fu L.; Bernstein, Aaron B.

The CHEDS researchers are engaged in a collaborative research project to study the properties of iron and iron alloys under Earth’s core conditions. The Earth’s core, inner and outer, is composed primarily of iron, thus studying iron and iron alloys at high pressure and temperature conditions will give the best estimate of its properties. Also, comparing studies of iron alloys with known properties of the core can constrain the potential light element compositions found within the core, such as fitting sound speeds and densities of iron alloys to established inner- Earth models. One of the lesser established properties of the core is the thermal conductivity, where current estimates vary by a factor of three. Therefore, one of the primary goals of this collaboration is to make relevant measurements to elucidate this conductivity.

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TYPE Other Report YEAR 2017
OSTIDOI

The Sandia Matlab AnalysiS Hierarchy (SMASH) toolbox

Dolan, Daniel H.; Ao, Tommy A.; Grant, Sean C.

The SMASH (Sandia Matlab AnalysiS Hierarchy) toolbox is a collection of MATLAB code for data analysis. The toolbox contains general purpose functions, custom class defini- tions, and self-contained programs aimed at the needs of experimental physicists working in pulsed power research. The initial release (version 1.0) supports file access, signal/image analysis, and user interface creation; custom graphics and generic system tools are also pro- vided. Much of the package is object oriented, encouraging users to build new capabilities from established classes. Future releases will continue this goal, expanding capabilities and streamlining application development.

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TYPE SAND Report YEAR 2016
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23 Results
23 Results