First Measurement of Z Opacity Sample Evolution near Solar Interior Conditions Using Time-Resolved Spectroscopy

Area of Science:

• Plasma physics
• Astrophysical modeling
• X-ray spectroscopy

Background:

• Opacity model discrepancies persist for iron at high temperatures (T>180 eV) and densities (ne>3x10^22 cm^-3), relevant to stellar interiors.
• Previous experiments relied on x-ray film, limiting temporal resolution.

Purpose of the Study:

• To investigate the role of temporal gradients in opacity model-data discrepancies.
• To present new measurements of opacity sample temporal evolution using advanced imaging technology.

Main Methods:

• Utilized novel hCMOS ultrafast x-ray camera technology for high-resolution temporal measurements.
• Measured opacity sample temporal evolution under high-temperature and high-density conditions.
• Analyzed measured conditions, backlighter time history, and modeled opacities.

Main Results:

• Demonstrated that temporal gradients do not resolve the long-standing model-data discrepancy in iron opacity.
• Provided the first measurements of opacity sample temporal evolution.

Conclusions:

• Temporal gradients are not the cause of the observed iron opacity discrepancies.
• The new hCMOS camera technology enables opacity measurements at more extreme conditions and spectral line shift analysis.