Liquid metal has been turned to plasma for the first time, with applications for attaining fusion energy.
Using high temperatures and high-density conditions, University of Rochester scientists in New York cooled liquid metal deuterium to 21 degrees Kelvin to increase its density.
They then used lasers to compress it to pressures up to 5 million times greater than atmospheric pressure, while increasing its temperature to almost 180,000 °F.
Mohamed Zaghoo, from the university’s Laboratory for Laser Energetics, said: "By monitoring the reflectance of the sample as a function of its temperature, we were able to observe the precise conditions where this simple lustrous liquid metal transformed into a dense plasma.
Liquid metals at high densities exhibit quantum properties. However, once the deuterium transitioned to a plasma state, those properties were lost, and instead exhibited classical properties.
Zaghoo said: “At about 90,000 °F, the reflectance of the metallic deuterium started rising with a slope that is expected if the electrons in the system are no longer quantum but classical.
“The conditions at which this crossover between quantum and classical occurs is different from what most people expected based on plasma textbooks.”
Rochester’s findings, which have been published in Physical Review Letters, could enable better understanding of stars and planets and help in controlled nuclear fusion, an alternative energy source.
“Plasmas comprise the vast interiors of astrophysical bodies like brown dwarfs and also represent the states of matter needed to achieve thermonuclear fusion. These models are essential in our understanding of how to better design experiments to achieve fusion,” Zaghoo said.
Plasmas – which consist of free moving electrons and ions that can conduct electricity – are the most abundant form of matter in the universe. Astrophysicists believe it to be the first of the four states of matter to be created after the Big Bang, preceding solid, liquid and gas.
Artificial plasmas have been created for plasma display panels in TV screens, neon signs and fluorescent lamps.