National Institute of Natural Sciences

Discovery of high-speed moving plasma turbulence for the first time in the world
Left: Forming a barrier in the plasma to confirm heat inside. Right: By breaking the barrier, turbulence was discovered that moves faster than the heat, as the heat escapes from inside the plasma. Credit: National Institute for Fusion Science

To achieve a fusion power plant, it is necessary to confine a plasma of more than 100 million degrees Celsius in a magnetic field for a long time. A research group led by Assistant Professor Naoki Kenmochi, Professor Katsumi Ida, and Associate Professor Tokihiko Tokuzawa of the National Institute for Fusion Science (NIFS), National Institutes of Natural Sciences (NINS), Japan, using measuring instruments developed independently and with the cooperation of It is expected that observation of turbulence will lead to the development of a method for real-time control of the temperature in the future.

In high-temperature plasma which is confined by the magnetic field, turbulence is generated. The turbulence causes the plasma to be disturbed, and the heat from the confined plasma flows out, resulting in a drop in the temperature of the plasma. Understanding the characteristics of heat and turbulence is needed to solve this problem. We don't yet have a full understanding of the turbulence in plasmas. The time evolution of minute turbulence with high sensitivity and extremely high spaciotemporal resolution is not well understood because it requires instruments that can measure it.

A barrier can form in the plasma that blocks the transport of heat from the center to the outside. The barrier creates turbulence by making a strong pressure gradient. A magnetic field structure has been developed by assistant professor Kenmochi and his research group. This method allows us to study the relationship between the heat and turbulence that flow as barriers break. We measured the changing temperature and heat flow of electrons and millimeter-sized fine turbulence using the world's highest level of accuracy. This experiment led to the discovery of turbulence moving ahead of heat at a speed of 40,000 kilometers per hour, which is about the speed of an airplane. The turbulence is close to a rocket.

The assistant professor says that the research has advanced our understanding of turbulence. The new characteristic of turbulence, that it moves much faster than heat, indicates that we may be able to predict temperature changes by observing turbulence. We expect to develop methods to control temperatures in real-time in the future.

Scientific Reports published the research.

More information: N. Kenmochi et al, Preceding propagation of turbulence pulses at avalanche events in a magnetically confined plasma, Scientific Reports (2022). DOI: 10.1038/s41598-022-10499-z Journal information: Scientific Reports Citation: Discovery of high-speed moving plasma turbulence that outpaces the movement of heat (2022, May 19) retrieved 19 May 2022 from This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.