New model improves understanding of how heat moves through fusion plasmas

October 22, 2021, 12:00PMNuclear News
Physicist Suying Jin with computer-generated images showing the properties of heat pulse propagation in plasma (Image: PPPL/Jin/Kiran Sudarsanan)

Researchers at the Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) have developed a new model of how heat flows within plasmas. According to PPPL, the model could improve insights into the behavior of plasmas and may help engineers avoid the conditions that could lead to heat loss in future fusion facilities.

Instead of using a single-fluid model that assumes that the heat flowing among electrons in plasmas was substantially unaffected by the heat flowing among the much larger ions, the new model takes into account the complex behavior of heat diffusion in electron-ion plasmas. By allowing for that interaction between the large-mass ions and smaller electrons, scientists can measure the temperatures of the particles more accurately, as well as infer information about one pathway from information about the other, according to PPPL.

The results of the research was reported in the paper “Coupled heat pulse propagation in two-fluid plasmas,” published in Physical Review E.

Changing channels: Suying Jin, a graduate student in the Princeton Program for Plasma Physics and lead author of the paper, said that the new model was informed from prior research into magnetic islands--plasma blobs formed from swirling magnetic fields--the modeling of which depends on accurate measurements of heat flow.

According to Jin, her team noticed gaps in how heat flow had been previously measured by others. “They had calculated the movement of heat assuming that it moved only through one channel,” she said. “They didn’t account for interactions between these two channels that affect how the heat moves through the plasma system. That omission led both to incorrect interpretations of the data for one species and missed opportunities to get further insights into the heat flow through both species.”

Nat Fisch, professor of Astrophysical Sciences at Princeton University and a coauthor of the paper, added, “It is remarkable that even minimal coupling between electrons and ions can profoundly change how heat propagates in plasma. This sensitivity can now be exploited to inform our measurements.”

Further research: According to PPPL, the new model will be used in future research. “We are looking at proposing another experiment in the near future, and this model will give us some extra knobs to turn to understand the results,” said PPPL physicist Allan Reiman, a paper coauthor. “With Jin’s model, our inferences will be more accurate. We now know how to extract the additional information we need.”

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