Scientists develop energy-efficient superconducting coil for advanced research

The coil of the prototype magnet is made up of superconducting magnesium diboride cables. Credit: CERN.

How can we push the boundaries of scientific research while using less energy?

CERN’s scientists are finding innovative solutions, with superconductivity playing a key role.

A team at CERN has successfully tested a new type of magnet coil that will significantly reduce power consumption in certain experiments.

This coil is made from magnesium diboride (MgB2) superconducting cables and will be used in the high-intensity electrical transfer line powering the High-Luminosity LHC (HL-LHC), the successor to the LHC.

The coil is set in a low-carbon steel magnetic yoke that holds and concentrates the field lines, in what is known as a superferric configuration.

This innovative magnet is being developed for the SHiP experiment, which aims to detect very weakly interacting particles and is scheduled for commissioning in 2031.

One of the SHiP detector’s two magnets needs to generate a field of about 0.5 tesla. Although this field is of moderate intensity, it must be produced in a huge volume, measuring 6 meters high and 4 meters wide and deep.

A conventional electromagnet would require over one megawatt of electrical power and, because it would need to operate continuously, its power consumption would be very high.

Superconductors, which conduct electricity without resistance and therefore without energy loss from heating, provide an elegant solution.

This principle is already used in LHC magnets, which are made from a niobium-titanium alloy and must be cooled to an extremely low temperature of -271 °C (2 Kelvin) using superfluid helium. This requires a complex cryogenic system.

MgB2 cables offer a significant advantage because they become superconducting at -253 °C (20 Kelvin) and can be cooled with gaseous helium. This method requires a less complex cryogenic system and offers better thermodynamic efficiency. While MgB2 cables cannot be used for accelerator magnets like those in the LHC, which generate fields of around 8 tesla, they are perfect for large magnets with moderate fields, such as the SHiP experiment.

Last September, a 1-meter-long demonstrator coil was built and has since passed operating tests, successfully cooling to temperatures of 20 to 30 Kelvin with gaseous helium.

Although many steps remain before the SHiP magnet is ready, these promising tests suggest that this technology could be used both at CERN and in industry.

“Such a magnet could consume up to 100 times less electrical power than an ordinary superferric magnet,” says Arnaud Devred, who leads the project with a team from CERN’s Magnets group.

“In the longer term, we could consider retrofitting certain magnets with MgB2 coils to reduce their electricity consumption. This project showcases the technological advancements for the HL-LHC.”

The superconducting links of the HL-LHC are garnering significant interest because they use high-temperature superconductors. Large-scale use of these superconductors could lead to substantial energy savings in many fields, including everyday life.

Thanks to this innovative development, the scope of this technology can now include electromagnets, with the SHiP spectrometer magnet being one of the first applications.