Magnetics Business & Technology - May/June 2020 - 20

RESEARCH & DEVELOPMENT

Fermilab Achieves World-Record Field Strength for Accelerator Magnet

Fermilab recently achieved a magnetic field strength of 14.1 teslas at 4.5 kelvins on an accelerator steering magnet - a world record.
Photo: Thomas Strauss
To build the next generation of powerful proton accelerators,
scientists need the strongest magnets possible to steer particles close to the speed of light around a ring. For a given ring
size, the higher the beam's energy, the stronger the accelerator's magnets need to be to keep the beam on course.
Scientists at the Department of Energy's Fermilab have announced that they achieved the highest magnetic field strength
ever recorded for an accelerator steering magnet, setting a
world record of 14.1 teslas, with the magnet cooled to 4.5 kelvins or minus 450 degrees Fahrenheit. The previous record of
13.8 teslas, achieved at the same temperature, was held for 11
years by Lawrence Berkeley National Laboratory.
That's more than a thousand times stronger magnet than the
refrigerator magnet that's holding your grocery list to your
refrigerator.
The achievement is a remarkable milestone for the particle
physics community, which is studying designs for a future collider that could serve as a potential successor to the powerful
17-mile-around Large Hadron Collider operating at CERN laboratory since 2009. Such a machine would need to accelerate
protons to energies several times higher than those at the LHC.
And that calls for steering magnets that are stronger than the
LHC's, about 15 teslas.

Magnetics Business & Technology *

May/June 2020

"We've been working on breaking the 14-tesla wall for several years, so getting to this point is an important step," said
Fermilab scientist Alexander Zlobin, who leads the project at
Fermilab. "We got to 14.1 teslas with our 15-tesla demonstrator magnet in its first test. Now we're working to draw one more
tesla from it."
The success of a future high-energy hadron collider depends
crucially on viable high-field magnets, and the international
high-energy physics community is encouraging research toward
the 15-tesla niobium-tin magnet.
At the heart of the magnet's design is an advanced superconducting material called niobium-tin.
Electrical current flowing through the material generates a
magnetic field. Because the current encounters no resistance
when the material is cooled to very low temperature, it loses no
energy and generates no heat. All of the current contributes to
the creation of the magnetic field. In other words, you get lots of
magnetic bang for the electrical buck.
The strength of the magnetic field depends on the strength of
the current that the material can handle. Unlike the niobium-titanium used in the current LHC magnets, niobium-tin can support
the amount of current needed to make 15-tesla magnetic fields.
But niobium-tin is brittle and susceptible to break when subject

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Magnetics Business & Technology - May/June 2020

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