Fig. 1: Interfacial thermal resistance platform.

a A 4 μm diameter tungsten wire coated with plastic (C₈H₄F₄) to an outer diameter of 125 μm is isochorically heated with copper He-α emission to high-energy-density conditions and imaged with Fresnel diffractive radiography using vanadium He-α emission through a narrow slit. b The delay of the backlighter beams, shown in red, is varied from shot to shot to image the target evolution after the heater beams, shown in blue. The X-ray framing camera integration time (dashed red line) starts 0.7 ns into the backlighter pulse when the probe X-ray emission is highest. c Due to its higher opacity, the tungsten will absorb significantly more energy, reaching an approximately 40 times higher temperature than the plastic. The tungsten expands rapidly until constrained by pressure equilibration with the surrounding plastic. The tungsten remains much hotter than the plastic, setting up a hydrodynamically stable interface that primarily evolves due to heat diffusion. d The imaged targets have sharp fringe features resulting from interference effects. For unheated conditions, the vacuum, plastic, and tungsten are all clearly differentiable with visible interfaces. After heating, multiple fringe features appear from the thermally induced pressure gradients at the interface and the shockwave driven by the tungsten expansion.