The powering up of HL-2M Tokamak, China’s newest nuclear fusion research device, last Friday was hailed by the country’s media as the “rise of an artificial sun”. It was not.

The sun has burned steadily for 4.6 billion years. The HL-2M experiment lasted only a few seconds (exactly how many, we don’t know).

Nor did the device’s technical specifications look impressive at first glance. The strongest electric current that can be generated by the facility in the southwestern city of Chengdu is between two and three mega-amps, for instance. The much larger Joint European Torus in Britain produced seven mega-amps, and is nearly 40 years old.

Nonetheless, the new facility is an important step in China’s plan to achieve commercial production of fusion energy by 2050, and suggests the country will keep faith in the idea even if some other countries abandon what some nuclear physicists view as a costly, risky and arguably hopeless cause.

When two atoms fuse to form a larger atom, they release an enormous amount of energy. Nuclear fusion was the energy source of stars, but to recreate the process on Earth and keep it under control so it will not explode remains a serious challenge.

The hot gas formed by fusing atoms burns or melts everything it touches, while the nuclear reaction generates a large amount of high-speed particles that could damage buildings or human tissue if not properly contained.

Despite the challenges, the Chinese government may proceed with building the China Fusion Engineering Test Reactor (CFETR) as soon as next year. The experimental reactor, which could take 10 years to build, would use extremely powerful magnetic fields to contain the hot gas or plasma.

The CFETR is aimed at solving the engineering problems involved in construction of a commercial power plant – such as keeping hot gas burning for months or years, and building structures durable enough to contain it. But the ambitious project faces two major uncertainties.

First, scientists do not know how long they can keep the reactor burning. A commercial reactor would need to run for years or even decades, and Chinese researchers are trying to find a solution at the Experimental Advanced Superconducting Tokamak (EAST) in Hefei, in the country’s southeast, which was built to make the fusion reaction last several minutes or longer.

The second uncertainty is about heat. Commercial fusion plants need to operate at a minimum of 10 times the temperature of the sun’s core. HL-2M, able to reach up to 200 million degrees Celsius (360 million degrees Fahrenheit), is the only facility in China capable of simulating that heat.

Together with EAST, this new facility would allow Chinese fusion scientists to try to solve some of the biggest challenges for CFETR, which is expected to start running in 2035.

Zhong Luwu, a lead scientist on the HL-2M project from the Southwestern Institute of Physics, told China National Radio that the device used some of the most advanced technology found in China, if not the world.
He said HL-2M could withstand repeated bombardment by the waste particles that can be produced by the hot gas, which carry a huge amount of energy.

But Wang Yugang, a professor of nuclear physics at Peking University, said some radioactive particles produced by fusion reactions could not be contained by HL-2M’s magnetic field.

“It is fine for short-term operation,” Wang said, adding that no man-made material could withstand the cumulative damage from subatomic particles over a period of years or decades. “It will take a long time to find [the right material].”

It has long been hoped that fusion energy could solve energy shortage problems. In theory, hydrogen from seawater could be used as fuel.

From the 1960s to 1990s, a large number of fusion research facilities were built around the globe. But in recent decades few new facilities have been added, because of a lack of progress and a waning of that hope.

The world’s largest fusion experiment, the ITER project (previously the International Thermonuclear Experimental Reactor) in southern France, has suffered severe delays and is without a clear date for completion.

The US government, a major contributor to that international project, has several times considered cutting financial support or withdrawing entirely.

“We all face similar technical challenges,” said a nuclear scientist from Tsinghua University who requested not to be named.

“If there is any difference here [in China], the government is willing to make a huge, persistent investment into a sector that may have little hope of generating any economic return for decades.”