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How does the strength of the magnets you use in research at the Lab compare with the strength of the magnets we have at home?

This month’s science question.
December 4, 2017
Sometimes people ask us a question and we try to answer them

An image from the National High Magnetic Field Laboratory in Tallahassee, Florida.

We routinely generate up to 65 Tesla but only for about 100 milliseconds.

Let’s start with some context. Magnetic fields are measured in Tesla, named after the scientist Nikola Tesla.

The field at the surface of a permanent magnet you have on your refrigerator is a small fraction (approximately 1/200th) of a Tesla. The Earth’s magnet field is an even smaller fraction of a Tesla (approximately 1/20,000), but with a rather large volume. You can buy super-strong permanent magnets that get close to 1 Tesla, and commercial superconducting research magnets run up to about 20 Tesla.

Research at our sister National High Magnetic Field Laboratory in Tallahassee, Florida, is conducted at up to 45 Tesla. The magnet used there can operate for hours at a time. The upper limits for such continuously operating magnets are dependent on the magnet being kept cold enough so the current powering the electromagnet doesn’t cause the system to overheat and melt.

At the National High Magnetic Field Lab Pulsed Field Facility here in Los Alamos, we focus on even stronger fields, and we get around the heat/cooling problem by pulsing our magnets for only very brief periods of time. We routinely generate up to 65 Tesla but only for about 100 milliseconds. At these field strengths, the challenge is containing the immense magnetic forces, requiring that we use some of the world’s strongest materials to, in turn, reinforce the pulsed magnetic field.

Back in 2012 we set a record here for the highest nondestructive field: 100 Tesla. That record has yet to be broken (but will be eventually). You can watch a video of what happened in the control room during that record-breaking experiment here.

Ross McDonald, National High Magnetic Field Laboratory, Los Alamos


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