China joined the international collaboration to build a giant fusion reactor in 2023, and has now achieved a milestone by generating a magnetic field for the first time, which is entirely new to this design. The “artificial sun” reactor, HL-3, is a tokamak reactor operated by 17 collaborative laboratories and facilities around the world. However, the much-hyped realization of using this giant reactor to produce energy is still more than a decade away, riddled with misinformation.
While HL-3 puts China in the vanguard of fusion research, it’s not the biggest reactor (yet), and the milestone is only in the reactor’s own timeline. The reactor is not yet in a stable operating state, producing energy comparable to the massive amounts of energy needed to run it and other similar reactors (known as tokamaks). But HL-3, like many tokamaks around the world, is seen as a proving ground for the technology that countries like China will provide to France’s truly world-leading ITER project. In that sense, their developments could make a big difference going forward.
A Tokamak is a doughnut-shaped (toroidal in scientific terms) vessel that holds a stream of superheated magnetic plasma, strengthened by giant magnets and a supercooled vessel. Plasma is a “cloud” of atoms that condense under star-like conditions, causing the same reactions that power real stars: atomic nuclei fusing together to release vast amounts of energy… in theory. We know it happens in stars, but we’ve never seen it happen inside a 1000-ton machine on Earth.
So what does it mean for a world-class “artificial sun” Tokamak reactor like HL-3 to establish a unique new magnetic field design? This is a major milestone in the field of Tokamak research, as the magnetic field is what actually confines the superheated fusion-produced plasma. Because the plasma reaches a million degrees, it cannot come into contact with other matter, or it will instantly cool out of its energy range if it does. and Magnetic fields will damage or destroy anything they touch, so tokamaks need the right magnetic field to contain the plasma and keep it hot enough to produce net energy.
There are a number of structural problems with the way tokamaks create their magnetic fields today. The extremely large electromagnets used in these machines are key to tokamak design (ITER introduced the most powerful electromagnets ever in 2021) and are constantly being developed. But they’re all either spaced individually around the tokamak’s shell, or simply built (by humans) from natural materials found on Earth, creating hotspots that block the plasma, like islands in a river.
In space, there are no stars trapped inside, so no such problem arises, but with generators, this is just another hurdle to overcome.
All this means that the new configuration of the magnetic field could be a big step forward, especially for HL-3, which is considered as a feeder technology for ITER. Chinese media reports that China has signed up to build the vacuum chamber module for ITER. The vacuum vessel is essential to ITER’s goals as it will allow it to safely carry out experiments to contain star-like reactions off the coast of France.
Both language barriers and state-run media make Chinese projects like HL-3 difficult to scrutinize, and there aren’t many meaningful comparisons between the dozens of projects currently underway around the world. China has one other operating fusion reactor that has attracted international attention (the Experimental Advanced Superconducting Tokamak, or EAST), which has been running on and off since the 2000s at China’s Hefei Institute of Physical Sciences.
But HL-3 belongs to a lineage of the Southwestern Physical Institute in Chengdu, 900 miles to the west, on the edge of China’s vast western region. That project also dates back decades, and both have undergone decades of major upgrades and rebuilds that have steadily increased their power. HL-3 is an improvement over earlier designs, and will likely result in a bigger machine and one with more total power.
We haven’t yet reached the threshold where a fusion reactor would produce more energy than it consumes, and to be honest, we don’t know if we’ll ever get there for sure. But with every step forward in proven tokamak technology, we’re getting closer to the possibility of fusion energy. And because we’re still so far away, every small step counts.
Caroline Delbert is a writer, an avid reader, and a contributing editor at Pop Mech. She’s also a fanatic about all things nuclear, cosmology, the mathematics of everyday things, and the philosophy behind it all.
