A worker at the Princeton Plasma Physics Laboratory peers into a device being used to develop nuclear fusion, a potential source of clean energy. (Elle Starkman/PRINCETON PLASMA PHYSICS LABORATO)

A l von Halle, an electrical engineer, stands over a waist-high twisted silver metal tube — his unfinished masterpiece — and says, “In the grand scheme of things, $80 million is not that much.”

That’s how much in federal funding his employer, the Princeton Plasma Physics Laboratory, would need to finish the device lying in three big pieces on a concrete floor. The thing has a stirring name: It’s a stellerator, or “starmaker,” designed to generate and contain a whirling, sputtering bit of the material that makes up the sun — superhot plasma.

Left incomplete in 2008 after running over its $75 million budget, the stellerator was supposed to be the next step in the United States’ long-running effort to develop a clean, nearly inexhaustible source of energy: nuclear fusion.

The cousin to nuclear fission — the force behind today’s nuclear power plants — fusion produces energy by smashing atoms together instead of splitting them apart. It’s the force that drives the sun and the stars, which spit out heat and light when hydrogen atoms collide and fuse. Fusion power — if it can ever be made to work — holds all the cards over fission. There’s no risk of Fukushima-style meltdowns. It produces just a smidge of radioactive waste, not tons of it. And it’s fueled by a form of hydrogen that is easily obtained from seawater rather than by uranium, which is expensive to process for fission.

After World War II, nuclear scientists exploited fusion reactions by creating hydrogen bombs, which make far bigger explosions than fission bombs.

Then in 1951, a Princeton University physicist, Lyman Spitzer Jr., conceived of a machine to harness this stunning power for peaceful purposes. He called it a stellerator, and he dreamed that each machine could provide electricity to tens of thousands of homes.

Six decades later, scientists at the lab Spitzer founded are worried that, as China, South Korea, Japan and Europe ramp up their investment in fusion research, the United States is backing away from his dream.

President Obama’s budget request for next year cuts domestic fusion research by 16 percent, to $248 million. It would shutter a fusion lab at MIT, one of four funded by the Department of Energy. It would slash 50 to 100 jobs from the 450 at the Princeton lab. And it would use the $48 million in total savings to boost the U.S. contribution to an international fusion mega-project now under construction in the south of France, called ITER, a project whose estimated costs have grown to $23 billion and whose start date has been pushed back to the next decade.

In a time of flat federal spending, the president has made a choice to fund the international project — whose costs to the United States will grow in coming years, according to Energy Department projections, to as much as $300 million a year — at the expense of the domestic program. (The United States pledged funding to ITER in 2003, joining the European Union, Russia, China, India, South Korea and Japan.)

This would be “devastating” to the community of several hundred U.S. scientists working on fusion energy, said Stewart Prager, the physicist who heads the Princeton lab. “We need clean, limitless power without greenhouse gases,” he said. “Year by year by year, the need for fusion just grows and grows and grows.”

The Princeton lab’s stellerator will not receive additional funding and so will remain unfinished, said Ed Synakowski, head of fusion research for the Energy Department. “Fusion is hard. The stakes are high,” Synakowski said. “But the potential payoff could be enormous for mankind.”

If the MIT lab is shuttered as planned — Congress has not yet voted on next year’s budget — fewer scientists will be drawn into the field, Prager says. And he worries that the United States will lose the expertise it needs to capi­tal­ize on lessons learned from ITER.

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.

Superhot plasma
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.’ ”