New reactor aims for fusion ignition

Posted by Emma Woollacott

Russia and Italy have agreed to build a new fusion reactor outside Moscow that they hope could become the first to achieve ignition - the point where a fusion reaction becomes self-sustaining instead of requiring a constant input of energy.

The design is based on MIT’s Alcator fusion research program, which in its present version - Alcator C-Mod - has the highest magnetic field and highest plasma pressure of any fusion reactor in the world.

Ignitor will be about twice the size of Alcator C-Mod, with a main donut-shaped chamber 1.3 meters across, and an even stronger magnetic field.

It will be much smaller and less expensive than the ITER project, which is not expected to achieve ignition.

The Ignitor reactor, says MIT physics professor Bruno Coppi, will be "a very compact, inexpensive type of machine," and could be ready to begin operations within a few years.

Its design offers especially good confinement of the plasma and a high degree of purity. It also has additional structures needed to produce and confine burning fusion plasmas in order to create the conditions needed for ignition, Coppi says.

"The whole point of Ignitor is to find out how a burning plasma behaves, and there could be pleasant or unpleasant results coming from it," says Roscoe White, a distinguished research fellow at the Princeton Plasma Physics Laboratory.

"Whatever is learned is a gain.  Nobody knows exactly how it will perform, that is the point of the experiment."

While emission-free power is obviously a goal, Coppi is especially interested in the potential of the new reactor to make new discoveries about fundamental physics.

Quoting the late MIT physicist professor Bruno Rossi, Coppi says, "Whenever you do experiments in an unknown regime, you will find something new." The new machine’s findings, he suggests, “will have a strong impact on astrophysics."