Quantitative radiography for determining density fluctuations in HED experiments

Area of Science:

• Physics
• Plasma Physics
• Astrophysics

Background:

• High-energy density (HED) experiments are crucial for understanding astrophysical phenomena and inertial confinement fusion.
• Instability growth and turbulence in HED systems present challenges for accurate modeling.
• Current methods for measuring turbulent mix are often limited in the information they provide.

Purpose of the Study:

• To develop a novel method for extracting quantitative density fluctuation measurements from X-ray radiographs.
• To utilize these measurements for constraining turbulent mix models in HED systems.
• To enable more accurate simulations and comparisons between experimental data and theoretical models.

Main Methods:

• Employs image filtering and correction for systemic effects (e.g., backlighter variations).
• Calculates density by analyzing X-ray transmission through multiple materials and using tracer materials.
• Generates an approximate single-material density field from which average density and density-specific-volume covariance (b) are derived.

Main Results:

• The method successfully extracts density fluctuation statistics, including average density and the b-moment, from single X-ray images.
• This provides significantly more information compared to traditional single scalar mix width measurements.
• Preliminary comparisons show that the data analysis method yields 1D average density and b curves consistent with simulations.

Conclusions:

• The developed method offers a powerful new tool for characterizing turbulent mix in HED experiments.
• The extracted density fluctuation statistics are valuable for validating and improving turbulent mix models.
• This advancement facilitates better initialization and comparison of hydrodynamic simulations with experimental data.