Plasma’s powers of 10 (phases)

Two men and a diagram with lots of colours. It ismade of distorted triangles
Physicists Hong Qin, left, and Yichen Fu with rendering of 10 phases of plasma from their Nature Communications paper. Credit: Photos and collage by Elle Starkman/PPPL Office of Communications.

A novel discovery suggests magnetised plasma has 10 unique phases, which is a small step on the path to harvesting the fusion energy of stars.

This is plasma in a magnetic field, which has weird effects on the geometric properties of atoms in the plasma. It is also the material from which stars are made.

In the study, published in Nature Communications, researchers from the US Department of Energy’s Princeton Plasma Physics Laboratory discovered a novel way of classifying these phases. This could help access the transitions between them, which support localised wave excitations.

“The paper is the basic theory, and the technology will follow the theoretical understanding,” says Hong Qin, co-author of the paper.

“The discovery of the 10 phases in plasma marks a primary development in plasma physics.

“The first and foremost step in any scientific endeavour is to classify the objects under investigation. Any new classification scheme will lead to improvement in our theoretical understanding and subsequent advances in technology.”

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Fusion combines light elements in the form of plasma to release massive amounts of energy. The team showed that the waves in magnetised plasma continually distort into 10 different shapes called “topological phases”, each of which was classified by the shape of the wave.

“The most important progress in the paper is looking at plasma based on its topological properties and identifying its topological phases,” says lead author Yichen Fu.

“Based on these phases we identify the necessary and sufficient condition for the excitations of these localised waves. As for how this progress can be applied to facilitate fusion energy research, we have to find out.”

“These findings could lead to possible applications of these exotic excitations in space and laboratory plasmas. The next step is to explore what these excitations could do and how they might be utilised.”

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