China’s BEST Fusion Device Park Enters Critical Assembly

China’s national major science project, the Compact Burning plasma Experimental Superconducting Tokamak (BEST), reached a significant milestone on Wednesday when its project park in Hefei was officially delivered and put into use, according to Xinhua. With the handover, construction of the device’s main machine has entered its most demanding phase—known as “four-ring nesting”—as China pushes to demonstrate fusion power generation by around 2030.

The park’s delivery, in Hefei’s “Future Science City” in Anhui Province, came ahead of schedule and coincided with the eve of China’s National Day. State broadcaster CCTV described the moment as an “important node” for the project, marking the transition from civil construction to the intricate assembly of the fusion device itself.

A Next-Generation Fusion Experiment

BEST is China’s independently developed next-generation “burning plasma” fusion experimental device. Its stated goal is to simulate the fusion reactions inside the sun to obtain what officials call a nearly inexhaustible source of clean energy.

The device—a tokamak that confines superheated plasma with powerful magnetic fields—is led in design by the Institute of Plasma Physics at the Hefei Institutes of Physical Science, Chinese Academy of Sciences (ASIPP). It is being built by Fusion New Energy (Anhui) Co., Ltd., a mixed-ownership enterprise founded in May 2023 with registered capital of 15 billion RMB that serves as ASIPP’s sole technology transfer platform for magnetic confinement fusion.

According to a technical overview, BEST is designed to fill the engineering gap between an “experimental reactor” and a “demonstration reactor,” moving fusion power generation from the laboratory toward commercialization. The machine’s main body measures 18 meters in diameter and 19 meters in height, with a total weight of approximately 6,000 tons. Its plasma targets a major radius of 3.6 meters and a minor radius of 1.1 meters, a maximum toroidal magnetic field of 6.15 Tesla, a plasma current of 4–7 MA, and a fusion power target of 20–200 MW.

Crucially, BEST aims to achieve advanced steady-state plasma performance—defined as a fusion energy gain factor (Q) greater than 1—along with high-Q fusion operation and research into real-time tritium production, extraction, and circulation. It is fueled by deuterium and tritium, and is designed for long-pulse operation exceeding 1,000 seconds.

The ‘Four-Ring Nesting’ Challenge

Since July 2026, multiple key core components of BEST have arrived on-site, and assembly has progressed steadily—reportedly more than half complete. Four sections of the vacuum main-machine components have been positioned and installed, and the first set of toroidal field (TF) magnets has completed all of its tests.

The device can be imagined as a giant, layered, nested thermos barrel. From the innermost vacuum vessel outward, the layers are nested in sequence:

• Vacuum vessel — the furnace chamber where fusion reactions occur.
• Cold shield — a super-insulation layer that blocks heat.
• Toroidal field magnets — which generate a super-strong magnetic field to trap the high-temperature plasma so it does not touch the vessel wall.
• Internal precision components — the additional parts installed inside the vessel.

The assembly of these nested layers is the “four-ring nesting” phase now under way. It is a demanding test of manufacturing precision, given that components must fit together within millimeter tolerances.

That precision was demonstrated in October 2025, when the cryostat base—BEST’s heaviest main-machine component and China’s largest vacuum component in the fusion field—was installed. The base, about 18 meters in diameter, roughly 5 meters high, and weighing more than 400 tons, sits at the very bottom of the main machine and carries nearly 6,700 tons of weight support and insulation, Anhui Daily reported.

“The cryostat base is the first large vacuum component of BEST’s main machine, with complex design conditions and hundreds of interfaces,” said Huang Xiongyi, BEST’s assembly and integration lead. “Its installation precision directly affects the stability and safety of the whole project.” The installation required surface level differences within 15 millimeters and positioning deviations of no more than ±2 millimeters, with the gap between the base edge and the machine pit shielding wall measuring less than 100 millimeters.

A Supply Chain Takes Shape

The BEST program has drawn in a broad industrial supply chain. On September 27, 2026, a delivery ceremony for the world’s first compact fusion device TF coil boxes was held at the Sinomach Heavy Equipment Deyang base, where eight TF coil box units completed manufacture and shipment, according to Tonghuashun. The D-shaped boxes are approximately 10 meters high, 5.5 meters wide, and 58 tons each.

The team overcame significant materials and manufacturing challenges, including optimizing a low-temperature, high-strength, non-magnetic stainless steel designated CHSN01 (N50), completing 30kW laser welding to control deformation of large D-shaped structures, and ensuring reliable operation at liquid helium temperature (4.2 Kelvin).

Other key suppliers include HeDuan Smart (vacuum vessel sectors), Aerospace Chenguang (cryostat system and bellows), the China Iron & Steel Research Institute (CHSN01 development), China Petroleum First Construction Company (general assembly), and Guizhou Aerospace Xinli (gravity supports).

A National Priority

The BEST milestone arrives amid a broader push by Beijing to elevate controlled nuclear fusion as a strategic technology. On September 30, 2026, at a State Council Information Office press conference, Science and Technology Minister Yin Hejun announced that during the 15th Five-Year Plan period (2026–2030), China will systematically deploy controlled nuclear fusion as a major basic research task, reported CNNPN.

The targeted breakthroughs include high-temperature plasma steady-state confinement, burning plasma physics, extreme-irradiation-resistant structural materials, high-temperature superconducting magnet engineering, and tritium self-sustaining breeding circulation. China also plans to advance AI for Science, using AI to predict plasma disruptions and actively control magnetic fields.

Minister Yin noted that China’s 2025 R&D investment reached 3.92 trillion RMB (2.8 percent of GDP), and that the country’s comprehensive innovation capacity ranked ninth globally. Vice Ministers Long Teng and Zhang Guangjun also spoke on major science infrastructure and international cooperation through the ITER project.

Hefei has become a national fusion hub, hosting the ASIPP, the University of Science and Technology of China, the EAST tokamak (known as China’s “Artificial Sun”), and the CRAFT facility. EAST has operated for more than 20 years, achieving milestones including 100-million-degree plasma operation and long-pulse, high-confinement modes that provided the physics basis for BEST.

Roadmap and What to Watch

According to Fusion New Energy’s three-step strategy, BEST is the first stage, to be followed by the Fusion Engineering Demonstration Reactor (CFEDR) and ultimately a first commercial fusion reactor. The company’s stated ambition is global commercial application of fusion energy within 20 years.

The roadmap calls for BEST to complete overall construction by the end of 2027 and to conduct a deuterium-tritium fusion power generation demonstration around 2030—potentially the world’s first such demonstration, aimed at verifying the feasibility of commercial controlled fusion power generation, CNNPN reported.

Many challenges remain. Controlled fusion requires stabilizing plasma at over 100 million degrees Celsius in a vacuum chamber for sustained, controllable output—a far cry from the instantaneous, uncontrolled release of a hydrogen bomb. It demands advances in superconducting magnets, heat- and radiation-resistant materials, and plasma control.

Still, the delivery of the BEST park and the start of the four-ring nesting phase mark a tangible step toward a technology that, if realized, would transform global energy. For now, the world’s attention will be on Hefei, where engineers are assembling the layers of a machine designed to bottle a star.