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Superconductor magnets have been greatly improved for fusion power plants

Superconductor magnets have been greatly improved for fusion power plants

New superconducting magnets ready for use in fusion reactors. This consists of a material that has yet to be cooled to a very low level, but not as much as previous components of this type.

Only 20 Kelvin

To build a tokamak-type nuclear fusion system, very strong magnets are needed. Its fields must be designed to keep the extremely hot plasma inside in a suspended state. This is because it must not come into contact with solid materials, as there are no known materials that can withstand temperatures of millions of degrees in the plasma core.

In order to achieve the required field strength, a superconducting magnet is used. In current systems, they must be permanently cooled to 4 K (-270 °C). The new material is called REBCO and was developed by a team of researchers at the Massachusetts Institute of Technology DevelopedOn the other hand, a temperature of “only” 20 K (-253 °C) is necessary.

This may seem like a relatively small difference, but in practice it has big advantages. Because in regions close to absolute zero, every degree of additional cooling must be paid for with high energy expenditures.

Many advantages

Furthermore, REBCO magnets are much easier to build. This means that the wires in the coil no longer have additional insulation. They can be used to build a low voltage system that is much easier to build than previous systems. Eliminating insulation also frees up some space for other components – such as cooling or materials for increased strength.

The prototype REBCO magnet for fusion systems, which weighs about 10 tons, was built in 2021. Tests showed that it is capable of generating a stable magnetic field with a strength of 20 Tesla. Since the first experiments, the limits of the magnets have also been tested in case something goes wrong. To do this, the team deliberately created unstable conditions, such as: b. The cooling device overheats and turns it off. This is the worst scenario that could happen in a fusion reactor and would also destroy the facility.


  • New magnets have been developed for fusion reactors
  • REBCO is cooled to 20 K instead of 4 K
  • The magnet keeps the plasma in suspension and is not allowed to be touched
  • REBCO magnets are easier to build, and no insulation is needed
  • The prototype shows a stable field of 20 Tesla
  • Simulated tests of overheating and cooling failure
  • The new technology offers significant advantages in practice

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