Testing the world’s most powerful magnet — Commonwealth Fusion

in today’s NYT: “Researchers at M.I.T.’s Plasma Science and Fusion Center and engineers at the company, Commonwealth Fusion Systems, have begun testing an extremely powerful magnet that is needed to generate immense heat that can then be converted to electricity. It would open the gates toward what they believe could eventually be a fusion reactor.

Fusion energy has long been held out as one of the most significant technologies needed to combat the effects of climate change because it could generate an abundance of inexpensive clean energy. Like traditional nuclear fission power, which splits atoms, fusion energy would not consume fossil fuel and would not produce greenhouse gases. It would be more desirable than nuclear fission because its fuel, usually hydrogen isotopes, is more plentiful than the uranium used by current nuclear plants, and because fusion plants would generate less-dangerous and fewer radioactive wastes.

Though a fusion energy breakthrough remains elusive, it is still held out as one of the possible high-technology paths to ending reliance on fossil fuels. And some researchers believe that fusion research could finally take a leap forward this decade.

Commonwealth’s new magnet, which will be one of the world’s most powerful, will be a crucial component in a compact nuclear fusion reactor known as a Tokamak, a design that uses magnetic forces to compress plasma until it is hotter than the sun. The reactor looks like a doughnut-shaped jar surrounded by magnets.

Commonwealth Fusion executives claim that the magnet is a significant technology breakthrough that will make Tokamak designs commercially viable for the first time. They say they hope it will be workable by 2025.

“If you go to a much higher magnetic field, you can go to a much smaller size,” said Bob Mumgaard, a plasma physicist who is chief executive of Commonwealth. He said that if it was possible to build a device just one-fiftieth the size of the planned reactor in France — which will be roughly as big as a soccer field — it would be able to generate almost as much power.

Commonwealth’s magnet will be one of 20 used to create a doughnut-shaped vessel in a space roughly the size of a tennis court. This year, Commonwealth established a 47-acre site in Devens, Mass., where it will build both its prototype reactor and a factory for the magnets. The magnets are made by depositing a thin film of exotic materials on a videotape-like backing that is then wound around a bottle that is used to contain the fusion reaction.

Commonwealth, which has raised more than $250 million so far and employs 150 people, received a significant boost last year when physicists at M.I.T.’s Plasma Science and Fusion Center and the company published seven peer-reviewed papers in the Journal of Plasma Physics explaining that the reactor will work as planned.

What remains to be proved is that the Commonwealth prototype reactor can produce more energy than it consumes, an ability that physicists define as Q greater than 1. The company is hoping that its prototype, when complete, will produce 10 times the energy it consumes.”