Experimentally Measuring Thermal Conductivity in Warm Dense Tungsten Using Fresnel Diffractive Radiography*

Transport properties in warm dense matter (WDM), such as thermal conductivity, have extensive theoretical predictions but lack experimental benchmarking [1]. We have developed a Fresnel Diffractive Radiography (FDR) platform at the Omega Laser Facility, which enables high spatial resolution measurements of the evolution of an isochorically-heated WDM interface [2-4]. Novel 1 µm-wide slits provide a spatially coherent X-ray source that, in the presence of sharp density gradients, result in distinct diffraction fringes. Isochoric X-ray heating of CH-coated metal wires sets up a temperature differential at the material interface. After pressure equilibration, the interface is hydrodynamically-stable, and the evolution of the interface is driven primarily through thermal conduction, which modifies the temperature and density profiles. We present results for the thermal conductivity of warm dense tungsten, obtained through analysis of the evolving diffraction pattern.

1) T. G. White et al. PTRSA 381, 20220223 (2023).

2) C. H. Allen et al. AO 61, 1987 (2022).

3) M. Oliver et al. RSI 93, 093502 (2022).

4) M. O. Schoelmerich et al. RSI 94, 013104 (2023).