Magnets pull China closer to fusion power

Scientists and engineers announced major progress in the development of two key superconducting magnets for future fusion reactors on Saturday, marking another step toward making fusion energy a practical source of electricity.

One of the breakthroughs involves a toroidal field superconducting magnet weighing 582 metric tons, developed by the Institute of Plasma Physics of the Chinese Academy of Sciences in Hefei, Anhui province.

Wu Yu, a researcher at the institute, said the magnet is currently the world's largest toroidal field magnet designed for a fusion reactor.

It passed a comprehensive review by an expert panel on Saturday.

"The volume of this magnet is 1.3 times that of the toroidal field magnet used in the International Thermonuclear Experimental Reactor, and its energy storage capacity is three times higher," Wu said.

The toroidal field magnet is one of the most important components of a fusion reactor.

It generates an extremely powerful magnetic field that keeps superheated plasma — a state of matter hotter than hundreds of millions of degrees Celsius — from touching the reactor walls.

This allows the fusion reaction to continue safely while reducing energy loss and damage to the reactor.

Because the magnet is expected to operate continuously for about 60 years, it must remain stable under extreme conditions, including ultralow temperatures, high electric currents, intense radiation and enormous mechanical stress.

The second breakthrough is a high-temperature superconducting central solenoid coil, which completed full-condition parameter testing on Saturday.

Scientists said its key performance indicators have reached world-leading levels.

"The central solenoid coil operates under the most demanding conditions in a fusion reactor," said Qin Jinggang, deputy director of the Hefei institute.

"It plays a critical role in starting and sustaining the fusion reaction," he added.

Qin said the coil is a key technology for moving fusion energy from laboratory experiments to practical electricity generation.

Researchers said the successive breakthroughs in the two core superconducting magnets have further strengthened the technological foundation for China's development of fusion reactors.

Song Yuntao, director of the Hefei institute, said the Burning Plasma Experimental Superconducting Tokamak, a major fusion research facility, is under construction in Hefei.

He said the facility aims to achieve net fusion power gain — producing more energy from fusion than is used to sustain the reaction — and demonstrate electricity generation by around 2030.

Fusion occurs when two atomic nuclei combine to form a heavier nucleus, releasing enormous amounts of energy. Scientists hope to reproduce the same process that powers the sun to generate carbon-free electricity on Earth.

If successful, fusion could provide a virtually limitless source of clean energy without carbon emissions while offering lower safety risks than conventional nuclear power.

The latest breakthroughs will significantly enhance China's capabilities in the independent research, development and engineering of fusion reactors, according to the Hefei scientists.

zhulixin@chinadaily.com.cn