The Helmholtz-Zentrum Dresden-Rossendorf has set a new world record for magnetic fields with 91.4 Tesla. To reach this record, Sergei Zherlitsyn and his colleagues at the High Magnetic Field Laboratory Dresden (HLD) developed a coil weighing about 200 kilograms in which an electric current can create the giant magnetic field for a period of a few milliseconds. The coil survived the experiment unscathed.
“With this record, we’re not really that interested in reaching top field values, but instead in using it for research in materials science,” explains Joachim Wosnitza, the HLD’s Director. The scientists are proud of being the first user lab to make such high magnetic fields available for research. Such high magnetic fields are generated by passing an electric current through a copper coil. But the magnetic field also influences the electric current because it tries to push the electric current out of the coil. The stronger the current flows, the more powerful these forces are. “At 25 Tesla, the copper would be torn apart,” Joachim Wosnitza explained.
“At 100 Tesla, though, the Lorentz force inside the copper would generate a pressure which equals 40,000 times the air pressure at sea level,” revealed Joachim Wosnitza. These forces would tear copper apart. That is why researchers use specific copper alloys that can withstand ten thousand times the atmospheric pressure. They then add a corset made from a special fiber that is typically used for bulletproof vests and which holds the alloy together from the outside. The HZDR technicians wind six of these special wires with corsets into a coil that has a hollow space of 16 millimeters at its center. This permits the generation of 50 Tesla within this special coil when a brief but powerful electric pulse flashes through the copper; a process that is over after a mere 0.02 seconds.
But that’s still far from the world record of 89 Tesla which the US held at Los Alamos for several years. And that is why the technicians put a second coil consisting of twelve layers of copper wire around the first one. This wire can only withstand 2500 times atmospheric pressure. But protected by a plastic corset, a current pulse lasting only a fifth of a second allows the creation of a 40 Tesla magnetic field inside the coil. Together with the 50 Tesla of the inner coil, this results in a world record of more than 90 Tesla.
This story is reprinted from material from Helmholtz-Zentrum Dresden-Rossendorf, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.