(ORDO NEWS) — For the first time, American physicists obtained a laser plasma with a high energy density, similar to that found in stars and nuclear explosions, and measured its parameters. It turned out to be a billion times denser than the plasma that feeds thermonuclear reactions in tokamaks. To date, this is the most extreme state of matter received on Earth. The results are published in the journal Physical Review Letters.
Plasma makes up 99 percent of the visible universe and is composed of freely floating electrons and atomic nuclei or ions. High Energy Density Plasma (HED) is a state of matter in the interior of stars where reactions like nuclear explosions take place. Unlike gaseous plasma in tokomaks – installations of magnetic thermonuclear fusion – this plasma is so dense that its properties are close to a solid.
“Things work differently in HED plasma,” first author Brian Kraus of the Department of Astrophysical Sciences at Princeton University said in a press release from the US Department of Energy’s Princeton Plasma Physics Laboratory (PPPL). works at such high densities, but until now these parameters have been difficult to measure. ”
Researchers from the Princeton Laboratory, together with colleagues from other laboratories and universities in the United States, have developed a new method for measuring the parameters of HED plasma. First, they generated plasma by hitting thin strips of titanium foil with an ultra-high-intensity laser, and then, using modern computers, they processed the high-resolution spectral data that an X-ray analyzer captured from the plasma that flared up for only a trillionth of a second.
“This allowed us to measure both the plasma density and the ion temperature, which we had never done before,” explains Kraus.
The study revealed key aspects of HED plasma that were not previously known. For example, the analysis showed that the temperatures of ions and electrons are not equivalent, as assumed, and the ions are much colder.
“From this we concluded that electrons and ions in such a plasma are not in equilibrium. This is the first time a similar situation has been observed in a plasma near the density of a solid,” notes Philip Efthimion, another study participant.
Scientists are currently setting up a new camera at Colorado State University with which they want to photograph the evolution of HED laser plasmas.
“This time we are experimenting with a new camera that can record time,” says Kraus. …
Also, the authors are developing software codes that will make it possible to create a digital model of the HED plasma.
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