Developing a platform for Fresnel diffractive radiography with 1 μm spatial resolution at the National Ignition...

Area of Science:

• Plasma Physics
• Materials Science
• X-ray Optics

Background:

• Warm dense matter (WDM) research requires precise diagnostics for material interfaces.
• Understanding thermal conductivity and diffusion is crucial for WDM evolution.

Purpose of the Study:

• To develop and demonstrate an x-ray Fresnel diffractive radiography platform for WDM studies.
• To measure micron-scale density gradient changes at material interfaces with high precision.

Main Methods:

• Designed an x-ray Fresnel diffractive radiography platform for the National Ignition Facility.
• Utilized Ti K-shell x-ray emission (4.75 keV) to heat a plastic cylinder with liquid D2.
• Employed Cu He-α x rays (8.3 keV) and a 1 μm slit for high-resolution radiography.

Main Results:

• Achieved precise tracking of the D2/plastic interface density gradients for several nanoseconds.
• Observed significant diffraction features in radiography, enhancing sensitivity to density scale length changes.
• Compressed liquid D2 to approximately 2.3 g/cm³ via cylindrical implosion.

Conclusions:

• The developed platform enables sensitive, high-precision measurements of WDM interface dynamics.
• Fresnel diffraction significantly boosts the platform's capability to detect subtle density variations.
• This technique advances the study of fundamental processes in isochorically heated materials.