• Heat transfer is impeded between materials in high-energy-density plasma due to interfacial thermal resistance.
• The research uses lasers to heat materials and observe heat flow (or lack thereof) at extreme temperatures.
• Findings have implications for inertial confinement fusion experiments and other technologies like semiconductor etching and hypersonic vehicles.

A new study supported by the U.S. National Science Foundation reveals that heat transfer is impeded in high-energy-density plasma. Researchers found that heat does not flow between materials at extreme pressures and temperatures. This is due to interfacial thermal resistance, a phenomenon that prevents heat flow between different materials in super-hot plasma. The research has implications for inertial confinement fusion experiments, semiconductor etching, and hypersonic vehicles.

• What: A study shows that heat transfer is impeded between materials in high-energy-density plasma due to interfacial thermal resistance.
• Who: Thomas White (University of Nevada, Reno), Cameron Allen, Jeremiah Williams (NSF)
• When: Published May 1, 2025; experiment conducted using lasers with progressively delayed timing.
• Where: Experiment conducted at the University of Rochester in New York using the Omega-60 laser.

The study's finding that heat transfer is impeded in high-energy-density plasma is significant because it challenges conventional understanding of heat flow in extreme conditions. The discovery of interfacial thermal resistance playing a crucial role in these environments has implications for various technologies, particularly inertial confinement fusion. Understanding how energy flows at boundaries in extreme environments is essential for advancing these fields.

"Understanding how energy flows across a boundary is a fundamental question, and this work provides us with new insights into how this happens in the exceptionally energy-dense environments that one finds inside of stars and planetary cores"

"When we looked at the data, we were totally shocked because the heat was not flowing between these materials. It was getting stuck at the interface between the materials, and we spent a long time trying to work out why."

"High energy laser labs provide an essential tool for developing a precise understanding of these extreme environments — and this has implications for a wide variety of important technologies, from medical diagnostics to national security applications"

The NSF-supported study demonstrates that interfacial thermal resistance significantly impedes heat transfer in high-energy-density plasma, challenging the assumption that heat flows unimpeded from warmer to cooler objects in dense plasmas. This discovery, documenting a phenomenon predicted over 200 years ago by Joseph Fourier, has critical implications for inertial confinement fusion experiments, potentially explaining discrepancies between simulations and experimental results, and impacting the design of multi-layered targets. Furthermore, the understanding of heat flow in extreme conditions is relevant to other technologies, including semiconductor etching and hypersonic vehicles. The observed electron scattering at material interfaces in super-hot plasmas highlights the need for further research to address the challenges posed by interfacial thermal resistance and optimize energy transfer in various high-energy-density applications.