Chinese tokamak achieves hydrogen-boron fusion with 100 million reactions a second

A clean energy firm in China has just achieved hydrogen-boron fusion reactions in the EXL-50U spherical tokamak, the nation’s first medium-scale spherical torus experimental device, at a rate exceeding 100 million per second.

Hebei-based ENN Group revealed that the experiment resulted in more than 100 million fusion reactions per second. It is the first hydrogen-boron fusion reaction achieved by a commercial fusion company on its own device.

Unlike deuterium-tritium (D-T) fuel, the primary fuel used in mainstream fusion research, hydrogen-boron fusion does not produce high-energy neutrons as its primary product. Instead a hydrogen proton fuses with a boron-11 nucleus. The reaction releases energy and produces alpha particles, or helium nuclei.

The company announced the achievement on Monday, September 28. According to the researchers, it could provide novel insights into hydrogen-boron fusion.

Fusion reaction milestone

Most fusion projects, including the International Thermonuclear Experimental Reactor (ITER) in France, focus on D-T fusion because it can be achieved under less demanding conditions than alternative fuel cycles. It combines a deuterium nucleus with a tritium nucleus, producing helium-4, a high-energy neutron, and 17.6 megaelectronvolts (MeV) of energy.

However, tritium is radioactive, scarce in nature, and expensive. D-T fusion also releases energetic neutrons that can damage the reactor materials and induce radioactivity in surrounding components. Hydrogen-boron fusion, by contrast, relies on comparatively abundant fuels and primarily produces charged alpha particles rather than high-energy neutrons.

the EXL-50U (ENN Xuanlong-50) was built between 2018 and 2019. Credit: ENN Group

However, hydrogen-boron fusion is considerably harder to achieve as it requires vastly higher temperatures and strict confinement conditions. So, instead of trying to raise the temperature of the entire plasma, the team combined high-energy neutral beam injection with radio frequency waves.

This stimulated particles in an energy range where hydrogen-boron reactions are more likely to occur, known as the first resonance peak. The process generated large numbers of energetic, or fast, protons in the plasma. These, then collided with boron nuclei and helped drive the fusion reaction rate beyond 100 million reactions per second.

A fusion power race

The company said more than 10 experts from international research institutes and universities reviewed the results. Meanwhile, repeatable measurements of alpha particles produced during the experiment provided evidence that the hydrogen-boron fusion reactions had, in fact, taken place.

Yang Yuanming, an ENN engineer who led the fusion project, said that hydrogen-boron fusion has attracted interest from private fusion developers, including US-based TAE Technologies and Germany’s Marvel Fusion. He stressed that hydrogen and boron fuels are abundant and readily accessible.

The approach could also offer another benefit. Hydrogen-boron fusion produces energetic charged particles. Future systems could potentially convert their energy directly into electricity, without using heat to make steam and power a turbine.

However, there are still technical hurdles to overcome before the reaction could be used in a practical power plant. The team is now working to push the plasma to more extreme conditions. “[We will] strive to get the plasma to 100 million degrees Celsius (180 million degrees Fahrenheit) as soon as possible,” Yang said.

SCMP reported that the company is also moving ahead with its next experimental platform. Earlier this month, it held a groundbreaking ceremony for Helong-2, its third-generation fusion device.