China has officially presented its next-generation fusion device, the HL-4 tokamak, which is designed to be the world's first facility to use high-temperature superconducting (HTS) magnets for steady-state burning plasma operations. The new machine builds on the operational experience of the HL-2M tokamak, located at the Southwestern Institute of Physics (SWIP) in Chengdu. The HL-4 project represents a significant step in China's national fusion energy program, which runs parallel to its substantial contributions to the ITER project. The use of HTS technology is a strategic choice aimed at overcoming the operational limitations of low-temperature superconductors and accelerating the development timeline for a commercially viable fusion power plant. Source: Tokamak Energy
The design parameters for HL-4 target a substantial increase in performance over its predecessor. The machine is engineered to sustain a plasma current of 5 million amperes (5 MA) within a 5 Tesla magnetic field. This is double the current achieved by HL-2M, which successfully produced discharges exceeding 2.5 MA. The predecessor device also demonstrated high-confinement mode (H-mode) operation for durations of over 10 seconds, a critical operational regime for maintaining a stable, high-temperature plasma. The advancements in HL-4 are intended to explore the physics of a continuously burning plasma, a necessary condition for a functional power reactor. Source: Tokamak Energy
The design parameters for HL-4 target a substantial increase in performance over its predecessor.
A key technological enabler for HL-4 is its reliance on high-temperature superconducting magnets. Unlike the low-temperature superconducting (LTS) magnets used in large-scale projects like ITER, HTS magnets can operate at warmer temperatures and generate stronger magnetic fields. This characteristic allows for a more compact device design and potentially more efficient, continuous operation without the extreme cryogenic demands of LTS systems. The adoption of HTS aligns with a broader trend in the private fusion industry, where companies like Commonwealth Fusion Systems are also developing HTS-based compact tokamaks to accelerate commercialization. The successful operation of HL-4's magnet system will provide critical data on the long-term performance and reliability of HTS technology at reactor scale. Source: Tokamak Energy
The HL-4 project is a core component of China's multi-pronged strategy for fusion energy development. This national strategy includes foundational research, participation in international collaborations, and the construction of progressively more advanced domestic machines. The ultimate goal is the China Fusion Engineering Test Reactor (CFETR), a planned device intended to demonstrate fusion electricity generation with a capacity of up to 1 gigawatt. The operational results from HL-4, particularly regarding steady-state plasma control and heat exhaust management with HTS magnets, will directly inform the final design and engineering of CFETR and subsequent demonstration power plants. Source: Tokamak Energy