Superconducting Magnet Sets 32-T World Record

One of the two YBCO coils used in the 32-tesla superconducting magnet. Image: Stephen Bilenky, MagLab

One of the two YBCO coils used in the 32-tesla superconducting magnet. Image: Stephen Bilenky, MagLab

The National High Magnetic Field Laboratory (CSA CSM) chalked up another world record in December when a new superconducting magnet at the facility reached a magnetic field of 32 teslas, a third stronger than the previous record and more than 3,000 times stronger than a common refrigerator magnet.

Researchers at the lab say the feat is important for both the new scientific discoveries it will enable and the even stronger superconducting magnets the technology foreshadows.

“The new system, and the magnets that will follow, will give scientists access to insights never before possible,” says physicist Laura Greene, the MagLab’s chief scientist. “We expect it to break new ground in a variety of research areas. Physicists are especially excited about advances in quantum matter, which features new and technologically important ultra-thin materials, as well as exotic new states of matter in topological materials and complex magnetic materials.”

For decades, the world record for a superconducting magnet has inched forward incrementally. Though eight years in the making, the single leap represented by the new magnet is bigger than all the improvements made over the past 40 years combined, according to the lab.

Engineers lower the 32-T into its cryostat. Image: MagLab

Engineers lower the 32-T into its cryostat. Image: MagLab

“This is a transformational step in magnet technology, a true revolution in the making,” says Greg Boebinger, MagLab director. “Not only will this state-of-the-art magnet design allow us to offer new experimental techniques here at the lab, but it will boost the power of other scientific tools such as X-rays and neutron scattering around the world.”

The 32-T is the third world-record magnet tested in the past 15 months at the MagLab, following a 41.4-T resistive magnet tested last summer and the 36-T series connected hybrid magnet that reached full field in November 2016. “We’re on a roll,” says Boebinger.

The new magnet represents a milestone for both low and high temperature superconductors, as MagLab engineers achieved the 32-tesla field by combining two sections, one LTS and one HTS.

There were three particular challenges to overcome in the design and manufacture of such a system, according to the lab, including the stresses within the magnetic coils, the management of the very high stored energy within the magnet and the integration of LTS and HTS coils.

Low temperature superconductors work only in extremely cold environments and generally stop working inside magnetic fields higher than about 25 teslas, a constraint that has limited the strength of superconducting magnets.

The LTS section in the 32-T system is an “outsert” that delivers 15 teslas in a 250 mm wide bore magnet. Engineers at Oxford Instruments Nanoscience (CSA CSM) developed the section using advanced LTS materials that operate at 4.2 K. The team also designed and tested both the cryogenic system and a new quench energy management system for the integrated magnet.

A team at the MagLab concurrently designed the system’s HTS “insert” section, which delivers 17 teslas in a 34 mm cold bore. It uses YBCO—a superconductor composed of yttrium, barium, copper and oxygen—manufactured by Superpower, Inc. (CSA CSM). The MagLab team worked for years with the tricky material—which is electrically and mechanically completely different than low temperature superconductors—to develop techniques for insulating, reinforcing and de-energizing the system.

“We greatly value our partnership with Oxford Instruments Nanoscience,” says Boebinger. “We celebrate together this new paradigm of integrating HTS and LTS coils with novel quench-protection technology to create a revolutionary 32-T magnet suitable for a wide range of scientific experiments. These are exciting times.”

The 32-T features a very stable, homogenous field suitable for sensitive experiments, according to researchers at the MagLab, combining both strength and stability. As with all magnets at the lab, scientists from across the world can apply to use it to explore new physics, chemistry and biology related to materials, health and energy. The new instrument is expected to be available to visiting scientists in the next year. And, through funding provided by the National Science Foundation and the state of Florida, researchers are able to conduct experiments for free.

For all its record-breaking impact, however, the 32-T is just the beginning, according to MagLab engineer Hubertus Weijers, who oversaw its construction. “We’ve opened up an enormous new realm,” he says. “I don’t know what that limit is, but it’s beyond 100 teslas. The required materials exist. It’s just technology and dollars that are between us and 100 teslas.” ■

Testing area for the 32-T. Image: MagLab

Testing area for the 32-T. Image: MagLab