Will this magnet make fusion on earth possible?

Jon Lawson
Image: Gretchen Ertl, CFS/MIT-PSFC

A device that produces more energy than it consumes does sound like the stuff of a fraud trial, but MIT and startup Commonwealth Fusion Systems (CFS) feel they are well on the way.

The technology is fusion: combining two small atoms to make a larger one, releasing large amounts of energy. The difficulty is containing material at 100,000,000ºC where this can happen.

To solve the problem the partners have looked to magnetism, and they have successfully performed a test run of a large high-temperature superconducting electromagnet with a field strength of 20 tesla. It’s claimed to be the most powerful of its kind. 

The magnetic fields form a container for the mix of protons and electrons, the plasma itself. As the particles have an electric charge, they are controlled by the magnetic fields, and one way of containing them is with a doughnut-shaped device called a tokamak. The MIT device is different to existing designs due to the high-temperature superconductors which allow a stronger field in a more compact space. 

Martin Greenwald, deputy director and senior research scientist observed, “The niche that we were filling was to use conventional plasma physics, and conventional tokamak designs and engineering, but bring to it this new magnet technology. So, we weren’t requiring innovation in a half-dozen different areas. We would just innovate on the magnet, and then apply the knowledge base of what’s been learned over the last decades.”

Now the magnet has proved stable, the team intend to continue refining it and create a prototype fusion generator by 2025.

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