Fusion’s Kept and Broken Promises

Soon, there may be a proving ground for her work and that of other physicists around the world: a reactor that dwarves MIT’s and every other magnetic reactor built. Among the rolling vineyards of Cadarache, in southern France, the United States and countries of Europe and Asia pooled funds to level a hilltop near a nuclear testing facility. They broke ground last year on the world’s largest magnetic fusion reactor, ITER. It has a bureaucratic name with a poetic soul, a name that may have been scribbled in a fit of responsible angst on graph paper at a Parisian café. It was conceived to stand for the International Thermonuclear Experimental Reactor, but it has since transcended acronyms and is defined now as Latin for “the way.”

It is likely that no machine has produced more power through fusion than was needed to start the reaction for more than a few seconds, but scientists at ITER believe they will achieve the dream for the first time. It is a simple matter of putting together the pieces and building on what is already known, they say. Like ordering a bike and assembling the parts. A multi-billion-dollar bike.

“There’s not much question, we know how to design the system. The challenge after we build it is to make it reliable,” says Gary Johnson a U.S. mechanical engineer in Cadarache. The issues ITER will lay to rest, he says, are the details of how to maintain a large fusion reactor, how to fix it and how to keep it running more often than it is under repairs. “I think no one will question that we’ll get it done,” Johnson says. “It’s like any new machine: you have to test drive it. On a machine as big and powerful as this we’ll be test-driving for years.”

Officially, it should cost about $14 billion, but insiders smirk at that figure. Obstacles ITER will have to surmount may be more prosaic than those that have stumped researchers in the past, but they are expensive. They have to order parts, for example, keep tabs on parts factories and determine which materials are best suited to line the tokamak and to build superconducting coils for the electromagnets.

In spite of the optimism, some believe materials may be more than an administrative chore. Dozens of labs around the world devise experiments to run at ITER, and Jon Menard’s lab at Princeton is one of them. ITER is designed to produce 500 megawatts of fusion power for up to 10 minutes, a feat Menard calls “a dramatic step forward.” But, he cautions, to take that power to the electricity grid, the machine would need to run continuously, with a plasma inside that donut so hot that it would cook whatever is surrounding it. Add to that the power collection. “Blankets” that trap the flying neutrons as they wheel away from fusing atoms and transfer the heat to a turbine have not yet been developed.

It’s depressing and exciting

Light pools around the base of the tokamak’s central pillar early into the first second of operation. The video is on a loop, replaying the same two seconds in slow motion on a monitor in MIT’s control room. As plasma cools, electrons glom onto their proton nuclei, firing off a photon of light as they join. The light in the video, therefore, reveals cooling plasma. The light climbs the pillar in a jittery, erratic way, flashing up and down, revealing glimpses of the tiled pillar behind, then drowns the views again as it flashes past. The counter reaches two and the video loops back to the beginning. Videos like this are a window into the plasma, a way to see the fusion reaction as it happens.

Over the decades since fusion power was first touted as a realistic technology, the public has learned to groan at each announcement of a breakthrough. Our high expectations were borne of unrealistic promises made early on and have been dashed by apparent stagnation. “I don’t think there are any major deal breakers and fusion could be part of our energy portfolio,” fusion critic Charles Seife says. “But I could have said that in the 1980s.”

There’s a body of meaningful knowledge undergirding the new sets of promises. And a lot of experts continue to believe in fusion as our chance for a clean energy future. But a lot of experts also smirk at the idea of seeing a dependable fusion plant within the next several decades. Magnetic fusion may be our best hope for a fusion power plant. Diplomatically, Menard sees a strength in both laser and magnetic technologies. “In my opinion, [laser fusion] is closer to demonstrating controlled thermonuclear ignition, but magnetic fusion is significantly closer to generating net electricity,” he says. It is closer, that is, to making a power plant.

“It’s one of those fields that’s depressing and exciting at the same time, because we’ve made so much progress, but there’s still so much to do,” MIT’s Andréa Schmidt says. “People don’t always have a lot of faith in us and it’s hard to get funding.” But, she adds, “With each new reactor we get closer and closer to our goal.”

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