Hydrogen has long been recognized as an important energy material and component in energy systems. As such, measuring and understanding its properties over a broad range of conditions is of fundamental interest. New work published in Physical Review Letters shows that hydrogen transforms to a dark fluid at high pressures and temperatures on the way to becoming a conducting fluid. 

The experiments were conducted by Stewart McWilliams (now at the Univesity of Edinburgh), as well as former postdoctoral associate Alan Dalton (now at the Defense Threat Reduction Agency), Alexander Goncharov (Carnegie), and Mohammad Mahmood (Howard University). EFree provided instrumentation for these and related experiments by the group. 

The team identified a form of fluid hydrogen that does not reflect or transmit visible light, but does transmit infrared radiation, and therefore heat. In addition to being important fundamentally, the measurements help to explain how heat can escape from gas giant planets, and how fully conducting fluid hydrogen deeper inside these bodies produces their large magnetic fields [R. S. McWilliams et al., Phys. Rev. Lett. 116, 255501 (2016)].