PLAINSBORO, N.J. — Hidden in the woods two miles from Princeton University’s main campus sits a drab white building easily mistakable for a warehouse. Inside is one of the Ivy League school’s most expensive experiments: a 22-foot-tall metal spheroid surrounded by Crayola-colored magnets. About half a dozen blue beams ring the sphere horizontally, while another set, painted red, rise vertically from the floor to wrap the contraption, like fingers clutching a ball.
Last fall, construction workers hustled to finish an upgrade to yet another magnet, this one jutting through the center of the sphere like a Roman column. On a recent November afternoon, Michael Williams, the lab’s head of engineering, weaved his way through workers and up a stainless steel scaffolding to get a better view.
“Fusion is an expensive science, because you’re trying to build a sun in a bottle,” Williams said.
This endeavor in the New Jersey woods, known as the National Spherical Torus Experiment, was created to study the physics of plasma, in the hopes that one day humans will be able to harness a new source of energy based on the reactions that power stars. The project has been shut down for two years to undergo an upgrade that will double its power. The improvement costs $94 million, and is paid for — like the rest of the Princeton Plasma Physics Lab — by the U.S. Department of Energy.
Impressive as it may appear, this experiment is small compared to what once stood there. Earlier in the day, while walking over to the site from his office, Williams pointed out a sign on the National Spherical Torus Experiment building that read “TFTR.” The abbreviation stands for Tokamak Fusion Test Reactor, a bigger, more promising fusion experiment that was scrapped in the mid-1990s.
“I keep telling them to take that down,” he said.
The history of the U.S. Department of Energy’s magnetic fusion program is littered with half-completed experiments and never-realized ideas. Currently, the most ambitious project in all of fusion work is the International Thermonuclear Experimental Reactor, or ITER, a collaborative scientific effort backed by the European Union and six other nations, including the United States. Once it’s built in southern France, ITER will be largest fusion reactor ever. The plans for this project dwarf the three similar U.S. fusion experiments, including the one at Princeton, in both scale and expense.
But ITER is sputtering with delayed construction and ballooning costs, and U.S. physicists are increasingly worried that their work at home, such as the National Spherical Torus Experiment, will be sidelined to fund the international project. They see the domestic research as crucial to understanding the nature of the plasma used in certain fusion reactions — crucial, even, to…