⚡ Two major problems of fusion reactors solved at once

Inside a fusion reactor, the plasma is heated to temperatures higher than those of the Sun. Part of this heat reaches the divertor, a system designed to remove waste. Without protection, this component can suffer irreversible damage. Additionally, plasma eruptions known as ELMs (edge-localized modes) can damage the reactor walls.

Researchers at the Institute of Plasma Physics in Hefei, China, led by Professor Guosheng Xu, implemented precise control of light gas injection into the EAST tokamak. This method created a regime called DTP (Detached divertor and Turbulence-dominated Pedestal). In this configuration, part of the plasma detaches from the divertor, reducing the thermal load, while microturbulences stabilize the edge.


The results are encouraging: the electron temperature in the pedestal increased, improving energy confinement. The ELMs completely disappeared, and the heat flux on the divertor dropped significantly. This was maintained for about one minute in a metal-walled environment.

This new regime relies on a delicate balance. The injection of light gases cools the plasma edge, but too much cooling would degrade performance. By adjusting the quantities in real time, the researchers achieved plasma detachment while strengthening the temperature gradient.

According to the scientists, this approach opens a promising path for future reactors. It combines effective divertor protection with high-performance confinement, two aspects often considered contradictory. The study, published in Physical Review Letters, thus represents a step toward stable and durable fusion plasmas.

The team from the Chinese Academy of Sciences emphasizes that this work demonstrates the feasibility of ELM-free operation while managing heat. The next steps are to extend the duration and to transpose this regime to larger reactors, such as ITER.