DgcitySuperconducting particle accelerators deliver intense beams, but they are tethered to liquid helium, a scarce and expensive coolant needed to keep their niobium cavities cold enough to conduct without resistance. A team in China has demonstrated an accelerator that breaks that dependence.
The Institute of Modern Physics of the Chinese Academy of Sciences and the Guangdong Provincial Laboratory of Advanced Energy Science and Technology announced that, after nearly a decade of work, they built and ran the world’s first helium-free superconducting electron accelerator using thin films of niobium tin, achieving stable beam transport.
Niobium tin becomes superconducting at a higher temperature than pure niobium. That higher operating temperature opens the door to cooling with mechanical cryocoolers instead of baths of liquid helium, fundamentally changing how a superconducting linear accelerator runs. The catch is that niobium tin is brittle and difficult to turn into the precise, smooth resonant cavities accelerators require, which is why the material challenge sits at the centre of the field.
The joint team worked through the underlying physics, the superconducting materials and the surface engineering together, developing the coating processes and equipment needed to deposit niobium-tin films on cavities and assembling a complete prototype. A review by the Chinese Nuclear Society concluded that the machine was the first anywhere to carry a stable beam in a niobium-tin superconducting accelerator and that the work reached an advanced international level, with parts leading the field. The effort produced more than a dozen granted patents.
The appeal of dropping helium runs deeper than convenience. Liquid helium supply is concentrated and price-sensitive, and large cryogenic plants add cost and complexity. Removing them could make superconducting accelerators practical in settings beyond big physics laboratories.
The shift in cooling is what makes the industrial uses plausible. A self-contained machine cooled by cryocoolers can in principle be installed at a hospital or an industrial site that could never support a liquid-helium plant, and it avoids the downtime that comes when helium supply chains tighten.
The team points to a broad list of uses: large-scale production of medical isotopes for diagnosis and targeted radiotherapy, radiation sterilization of supplies, treatment of hard-to-process pollutants, inspection of special components, and irradiation to preserve food and medicines. A proven prototype is still far from a commercial machine, and durability over long operating periods must still be demonstrated, but it establishes the principle that a next-generation accelerator can run without a helium infrastructure behind it.
