China unveils HL-4 tokamak as world's first HTS steady-state ‘burning' fusion facility
Interesting Engineering
China has shown off plans for HL-4, a new fusion reactor in Shanghai. It’s built to run continuously with superconducting magnets, a first for this kind of machine.
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China has pulled back the curtain on HL-4, its next big fusion reactor, with blueprints and concept art shown at the Shanghai Fusion Energy Conference & Fusion Week 2026. The project is being built in Shanghai and is meant to push tokamak research past a problem that has dogged earlier machines: they get hot, and then they have to stop.
Tokamaks try to recreate the fusion process that powers the sun by trapping superheated plasma inside powerful magnetic fields. The name Huanliu, the Chinese term behind the HL series, refers to circulation or toroidal flow, which is a neat way of saying the plasma is being forced around in a donut-shaped loop. China has been working on this line of reactors for decades, with the Southwestern Institute of Physics in Chengdu leading the Huanliu series since the 1980s.
HL-3, the current step in that line, can mimic some of the physics of a true burning reactor, but it still relies on conventional copper coils. That matters because copper overheats quickly, which means the machine cannot keep running continuously. HL-4 is supposed to fix that by becoming a steady-state burning experimental platform with high-temperature superconducting magnets.
The headline number here is 25 tesla, the magnetic field the new system is designed to generate. China Fusion Energy says that stronger field helps trap the plasma while also shrinking the reactor’s size, which in turn could make technical testing move faster. The project also folds in AI-driven intelligent operation technology, and the stronger magnets should let researchers probe plasma behavior under conditions they could not reach before.
There is still a lot of hard engineering ahead. Teams are already doing preliminary process development on site, and researchers are due to move next year into a purpose-built facility in Shanghai. CGTN says the R&D team will shift into a new 500-meter-long super factory by June next year, where full-scale magnet manufacturing and testing will begin.
For now, HL-4 is not the finish line. Chinese researchers describe it as a validation step, built to prove that high-temperature superconducting magnets can work reliably in complex fusion conditions. If that checks out, the next stop is a demonstration reactor, and only after that does the commercial phase begin.
My take — AI-written commentary, not fact-checked reporting
This is the right place to spend fusion money: on the ugly middle part where magnets, heat and reliability stop agreeing with the slide deck. HL-4 sounds less like a miracle machine than a very expensive argument that superconducting hardware can survive reality, which is exactly what fusion has been missing. The sector needs more of that and less cosmic branding.
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