Already, the United States has cut way back on investment in fusion. In the 1980s and early 1990s, the Energy Department spent about three times more than it does now.
Progress has been slow, and the technical hurdles remain high. Even Prager, the most optimistic of fusion scientists, says that a fusion reactor that could pump electricity into the grid wouldn’t be feasible until at least 2035 — and that’s only with the help of generous funding.
The main challenge is handling superhot balls of gas called plasmas. In another big room at the Princeton lab sits a two-story-tall, apple-shaped device that’s designed to do just that. Known as the National Spherical Torus Experiment, the machine is out of commission until 2014 for a $94 million upgrade that will more than double its power.
Inside its silvery vacuum chamber, microwaves and other sources of energy will excite hydrogen atoms to temperatures hotter than the sun. As these atoms fuse, a hard-to-control plasma will pop into existence.
Magnetic fields will squeeze this plasma to keep it contained. “It’s like trying to hold jello with rubber bands,” says Mike Williams, the lab’s head engineer. “How do you do that in a stable way?”
No one has a complete answer yet. Even when the upgrade is complete, the device will produce a plasma for just five seconds at a pop.
The goal of the ITER experiment is to produce a plasma for 10, 20, 30 seconds, maybe a minute. If successful, ITER will be the first plasma that generates more power than it consumes — although it won’t generate electricity. For future fusion power plants, such plasmas will have to be kept going indefinitely.
Then would come more challenges: What materials can withstand that sustained heat? And how will this heat be converted into electricity?
Fusion scientists have plenty of possible solutions they want to test, said George “Hutch” Neilson, the Princeton lab’s deputy head. But he said there is no national or international road map for moving from the relatively small plasma experiments of today to the operational power plants of tomorrow.
“There’s enormous debate on how to get there,” says Prager.
And little political support in the United States for the needed investment.
Obama has said that he favors an “all of the above” energy strategy: more drilling for gas and oil, more investment in solar and wind, more traditional nuclear. Fusion, however, is absent from the list.
Energy Secretary Steven Chu rarely mentions it. But at a March Senate hearing on his agency’s budget request, Sen. Diane Feinstein (D-Calif.) forced the Nobel Prize-winning physicist to address the president’s proposed cuts.
Chu said, “[W]e are working . . . to see if we [can] satisfy both the needs of the fusion community in the U.S. and this ITER commitment, but in these tight budget times, it’s tough.”
In February, the nation’s top fusion scientists met at an Energy Department advisory committee meeting. For hours they wrangled with the “doom and gloom” of the budget proposal, said Martin Greenwald, an MIT plasma physicist and head of the committee.
Then the leader of China’s fusion program, Jiangang Li, addressed the group. He said that China is committed to producing 2,000 new fusion scientists and that fusion research enjoys strong political and financial support from “the top leaders all the way up to the president,” according to minutes from the meeting. He described a billion-dollar plasma experiment now underway and plans for bigger experiments.
One of the committee members, Amanda Hubbard of MIT, then spoke up, replying that the contrast with the U.S. fusion plan, “or lack of a plan,” was striking.
Said Greenwald: “[Li] basically said, ‘Thanks for 60 years of research; we’ll take it from here.’ ”