Argonne at 50

Argonne builds a tradition of world-class superconducting magnets

ARGONNE, Ill. (Aug. 31, 1996) — Fifteen years ago on this date, the largest, most powerful superconducting dipole magnet ever built set a world record that still stands today.

The magnet, designed and built by Argonne National Laboratory near Lemont, generated a magnetic field of 6 tesla -- some 180,000 times stronger than the earth's magnetic field, and the strongest field yet generated by a magnet of its type.

The magnet looked like an immense stainless-steel can tilted on its side, with a hole bored through the middle large enough for a small child to walk through. It was about 22 feet long, 13.5 feet wide, 16 feet tall and weighed 200 tons.

Successful testing of the huge magnet was a milestone in the development of U.S. magnet technology and a major accomplishment in Argonne's long and continuing history of developing record-setting superconducting magnets.

Superconductors lose all resistance to electricity when cooled to near absolute zero -- about 459 degrees below zero Fahrenheit. They make compact, energy-efficient electromagnets that use far less energy and create more powerful magnetic fields than larger, heavier magnets that use conventional materials.

As far back as 1965, Argonne had been the world's first laboratory to use a superconducting magnet in a full-scale high-energy physics experiment. At the time, Argonne operated the Zero Gradient Synchrotron (ZGS), a 12.5 billion-electron-volt particle accelerator. The superconducting magnet was used in an instrument that detected basic particles of matter produced during high-energy-physics experiments.

In the late 1960s, Argonne built what was then the world's largest superconducting magnet -- it weighed 107 tons -- and installed it around a 12-foot bubble chamber, another high-energy-physics particle detector. In 1970, this instrument recorded the first creation of a neutrino in a liquid hydrogen chamber.

The 200-ton dipole magnet that set the world's record 15 years ago was built for research on magnetohydrodynamics (MHD), a clean-coal-burning technology that produces electricity without the turbines that conventional power plants use.

Instead, it passes a gas of charged particles at high speed through a magnetic field. The field generates an electrical current in the gases, which is drawn off by electrodes.

The U.S. MHD technology development program was recently canceled. The program succeed in proving that the basic concept works, but the rate of progress was judged to be faster for other, equally promising energy technologies.

Still, Argonne's expertise in building superconducting magnets made important contributions to understanding this area of applied energy research, as well as to basic research on the fundamental nature of matter and the universe.

Today, Argonne remains a world leader in developing superconducting magnets -- but of a new type based on a new generation of "high-temperature" superconductors.

These new materials, discovered only 10 years ago, lose all resistance to electrical current when cooled by liquid nitrogen, a material that costs much less and is much easier to handle than the liquid helium needed to cool earlier "low-temperature" superconductors.

High-temperature superconductors promise such technological advances as more efficient electric motors and generators, magnetic energy-storage devices, smaller and faster computers, and power lines that could carry electricity hundreds of miles with little or no energy loss.

But first, ways must be found to turn these brittle ceramics into long lengths of flexible wire that can carry useful amounts of current and can be wound into coils for magnets and generators.

This year, Argonne has combined with Intermagnetics General Corp. (IGC) of Latham, N.Y., to build a magnet that set two U.S. records for the highest magnetic fields ever generated by a coil made of high-temperature superconductors: 4.2 tesla when cooled by liquid helium, and 0.49 tesla when cooled by liquid nitrogen.

These fields are smaller than those produced by the earlier generation of low-temperature superconducting magnet. But high-temperature superconductors are a new technology, and Argonne continues as a world leader in helping turn them into practical devices, all the while building on its long tradition of making state-of-the-art superconducting magnets.

The nation's first national laboratory, Argonne National Laboratory conducts basic and applied scientific research across a wide spectrum of disciplines, ranging from high-energy physics to climatology and biotechnology. Since 1990, Argonne has worked with more than 600 companies and numerous federal agencies and other organizations to help advance America's scientific leadership and prepare the nation for the future. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.

For more information, please contact Catherine Foster (630/252-5580 or cfoster@anl.gov) at Argonne.