Pulsed-power facility explores elusive warm dense matter regime

At the intersection of the realms of condensed matter and hot plasma lies the regime of warm dense matter (WDM). This describes matter too hot to be easily described by condensed matter theories, but too dense to fall under the umbrella of plasma physics. Probing this regime experimentally has also been challenging, leaving this temperature and pressure region largely unexplored.

To gather more experimental data on WDM, Jodar et al. developed a pulsed power facility capable of applying multiple optical and electronic diagnostics and accessing a large thermodynamic range.

“By reaching and probing unexplored thermodynamic states, we hope to guide theoretical research on density functional theory and average atom calculations in a temperature and density range where they do not match yet,” said author Benjamin Jodar.

The researchers’ experimental facility consists of a metallic foil sandwiched by a sapphire anvil and heated by a kiloamp electrical pulse. This setup allowed the team to precisely control the density and pressure of the sample. In experimental tests, they collected direct measurements of tension, current, pressure, and particle velocity on aluminum to evaluate its equation of state and DC conductivity.

The authors plan to further improve their facility by expanding its functional range and increasing its diagnostic capabilities.

“We are currently working on improving the capabilities to reach warmer temperatures and higher pressures,” said Jodar. “Simultaneously, work is in progress for implementing a temperature diagnostic that will help us assess the temperature of the plasma and its emissivity. We will also try to couple our experiment to a synchrotron source to probe the plasma electronic structure by X-ray absorption spectroscopy.”

Source: “A pulsed power facility for studying the warm dense matter regime,” by B. Jodar, L. Revello, J. Auperin, G. De Lachèze-Murel, A. Marizy, T. Géral, E. Lescoute, J.-M. Chevalier, C. Blancard and L. Videau, Review of Scientific Instruments (2024). The article can be accessed at https://doi.org/10.1063/5.0220607 .