China unveils HL-4 fusion reactor concept with 25-tesla superconducting magnets

September 20, 2026 at 01:48 AM2 min

This digest was compiled by AI from multiple sources — links to the originals are below.

China has unveiled the concept for HL-4, a next-generation experimental fusion reactor with a fully superconducting magnet system designed to reach 25 tesla. The design was presented at the Shanghai Fusion Energy Conference & Fusion Week 2026. The project aims to test long-duration steady-state plasma operation, a key requirement for future burning-plasma reactors.

Key Facts

HL-4 is designed with a fully superconducting magnet system targeting a maximum magnetic field of 25 tesla.
The concept was presented at the Shanghai Fusion Energy Conference & Fusion Week 2026.
The research team is scheduled to move to a new specialized site in Shanghai in 2027, where a production and research complex about 500 meters long is under construction.
HL-4 will use artificial intelligence algorithms to control tokamak parameters and plasma state during experiments.
HL-4 is not a commercial fusion power plant project.

HL-4 Design

HL-4 continues the Huanliu series of Chinese experimental fusion devices developed since the 1980s by the Southwestern Institute of Physics (SWIP) in Chengdu. The name Huanliu translates as 'circulation' or 'toroidal flow', referring to the ring-shaped tokamak chamber. The previous device, HL-3, uses conventional copper magnets that heat up during long operation, limiting experiment duration. HL-4 is intended to overcome this limitation with a fully superconducting magnet system. Developers describe HL-4 as the first experimental platform of its type to combine high-temperature superconductors, a strong magnetic field, and a focus on steady-state regimes.

Magnet Development

Building magnets capable of producing up to 25 tesla and operating reliably in a fusion environment is a major engineering challenge. A primary goal of the project is to verify the long-term performance of high-temperature superconductors under such conditions. In 2027, the research team plans to relocate to a new specialized site in Shanghai. A production and research complex about 500 meters long is under construction there for full-scale manufacturing and testing of magnet systems.