Magnetics Business & Technology - Winter 2017 - 14

RESEARCH & DEVELOPMENT
Mini Magnet Packs World-Record, One-Two Punch
Sometimes, the best things come in small packages. That was
the case January 18 at the National High Magnetic Field Laboratory
when a magnet that fits in the palm of your hand claimed a new
world record.
Made of high-temperature superconducting (HTS) tape, the
miniature magnet is only the second of its kind ever made. Outperforming its MagLab predecessor, it reached a magnetic field of 11.3
teslas (or T, a unit of magnetic field strength) while inside a larger,
31.2-T resistive magnet. Operating as one 42.5 T "hybrid" magnet,
this test instrument achieved two records at once. First, the 42.5
T field is the highest field in which a superconducting magnet has
ever operated. Second, 42.5 T is a new world record for an HTS
magnet operating within a background field.
The new record was within striking distance of the 45-tesla
hybrid magnet, which holds the Guinness World Record for any
continuous-field magnet, held by the National MagLab since 1999.
"We are this close," said the new magnet's designer, MagLab engineer Seungyong Hahn, as he held up an index finger and thumb as
if applying a pinch of salt. "It's really good motivation for the next
attempt."
Hahn has pioneered the "no-insulation" technique to which the
magnet owes its slim profile: It looks like a toy next to the traditional superconducting magnets (made of niobium-tin and niobiumtitanium) that it may one day make obsolete.
Until now, engineers have woven insulators between the conducting layers of a magnet to direct the electric current that creates the
magnetic field. But Hahn, a professor at the FAMU-FSU College of
Engineering, came up with a design that jettisons the insulation, allowing engineers to pack far more conductor, and therefore more
current to generate higher fields, into a smaller area (see illustration below). This provides more options on how to design even
stronger magnets, said MagLab engineer Iain Dixon, who oversaw
the new magnet's construction.

In this latest test, the REBCO superconductor demonstrated an
unheard-of current density - the amount of electricity passing
through a conductor's cross-section. The copper wire in your home
has a current density of about 4 amps per square millimeter. Other
HTS magnets have exhibited current densities of about 200 amps
per square millimeter. The new no-insulation magnet reached a current density of 1,100 amps per square millimeter.
"No one ever designed any magnet - any kind of magnet - with
such a high current density," said Hahn. "It's a different level than
people can even imagine."

You could easily hold the 5-cm-long, no-insulation magnet in the
palm of your hands
Unlike many other superconducting materials used in magnets,
REBCO continues to operate even in the presence of very high magnetic fields, allowing REBCO magnets to be paired with very strong
superconducting magnets to generate very large fields.
The MagLab is now building a smaller version of this hybrid
magnet slated to become available to scientists later this year. The
20-T system will help researchers and engineers learn more about
how to operate a no-insulation coil and what science it can yield.
The new record magnet was the result of close collaboration
between the MagLab's Applied Superconductivity Center and Magnet Science and Technology division. The team will continue to
work on technical issues - improving the joints between sections
of superconductor and the cooling system - as they build the magnet's third iteration.
It's all part of being on the cutting edge of technology.
"Everything is the first time," Hahn said, "so even we don't even
understand everything at the moment."

Imaging Breakthrough Reveals Magnets' Internal Patterns

Engineers are confident this new HTS magnet, made of rareearth barium copper oxide (REBCO) shaped into an extremely thin
(0.042 mm) tape, will help the MagLab surpass the record held by
the 45-tesla hybrid, built using an older, far bulkier technology.
"We're pushing to go beyond 45 T," said Dixon. "Because this
technology makes such compact coils, it's a way we can actually
fund stronger magnets. This technology looks like the best way of
achieving that."

Magnetics Business & Technology * Winter 2017

A new imaging technique has helped scientists make a breakthrough in how they visualise the directions of magnetisation inside
an object.
Magnets play a vital role in everyday life, are used in everything
from hard drives to energy production, and scientists have already
been able to study the structure of thin films of magnetic materials.
However, imaging the inner structure of thicker forms of magnets
had remained an experimental challenge until now. A better understanding of magnets could contribute to the creation of better
motors, more efficient energy production, and hard drives capable
of holding more data.
In a new paper published in the journal Nature, scientists based
in Scotland and Switzerland describe how they have used tomography and high energy x-rays, combined with a novel reconstruction
algorithm, to peer inside and reconstruct the magnetic structure of
a micrometre-sized 'pillar' of gadolinium-cobalt magnetic material
for the first time.

www.MagneticsMag.com

http://www.MagneticsMag.com

Table of Contents for the Digital Edition of Magnetics Business & Technology - Winter 2017