200-Year-Old Heat Transfer Theory Confirmed in High-Energy-Density Plasmas

A phenomenon described by Joseph Fourier over 200 years ago, interfacial thermal resistance (ITR), has been documented for the first time in high-energy-density (HED) plasmas by researchers at the University of Nevada, Reno, and Los Alamos National Laboratory. The findings, published in Nature Communications, reveal that heat flow is impeded between materials at extreme pressures and temperatures, such as those found in fusion experiments and planetary interiors. Using the Omega-60 laser at the Laboratory for Laser Energetics in Rochester, NY, the team, led by Thomas White and Cameron Allen, heated copper foils with an energetic laser to emit X-rays, which then heated a tungsten wire next to a plastic coating. Surprisingly, heat transfer between the tungsten and plastic was significantly hindered. White explained that electrons carrying thermal energy scatter at the interface, preventing efficient heat flow. This discovery has significant implications for inertial confinement fusion experiments, where multi-layered targets are used. Understanding ITR could resolve discrepancies between simulations and experimental results. Jeremiah Williams, National Science Foundation Plasma Physics Program Director, noted the work provides new insights into energy transfer in extreme environments, with implications for technologies ranging from medical diagnostics to national security.