Magnetic Levitation for Fusion Energy

Experimental machine that mimics a planet’s magnetic field is designed to tame nuclear fusion for power generation

MIT

It’s amazing no one thought of it before: nuclear fusion from a levitating tire-sized magnet surrounded by 10-million-degree plasma. But that’s exactly what a joint project between MIT and Columbia University are tinkering with over at MIT’s Plasma Science and Fusion Center.

Using a donut-shaped half-ton magnet made of superconducting wire coils, researchers are replicating the magnetic fields of planets to manipulate super-heated gases in an experiment that could lead to a breakthrough in nuclear fusion based power. The Levitated Dipole Experiment (LDX) reactor is housed inside a 16-foot-diameter steel structure in a building on the MIT campus.

When operating, the huge LDX magnet is supported by the magnetic field from an electromagnet overhead, which is controlled continuously by a computer based on precision monitoring of its position using eight laser beams and detectors. The position of the half-ton magnet, which carries a current of one million amperes (compared to a typical home’s total capacity of 200 amperes) can be maintained this way to within half a millimeter. A cone-shaped support with springs is positioned under the magnet to catch it safely if anything goes wrong with the control system.

Levitation is crucial because the magnetic field used to confine the plasma would be disturbed by any objects in its way, such as any supports used to hold the magnet in place. In the experimental runs, they recreated the same conditions with and without the support system in place, and confirmed that the confinement of the plasma was dramatically increased in the levitated mode, with the supports removed. With the magnet levitated, the central peak of plasma density developed within a few hundredths of a second, and closely resembled those observed in planetary magnetospheres (such as the magnetic fields surrounding Earth and Jupiter).

MIT News

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