PPPL technician Doug Voorhees works on one of the stellerator’s 18 coils. The project is being shut down.
PPPL technician Doug Voorhees works on one of the stellerator’s 18 coils. The project is being shut down.
Elle Starkman, courtesy Princeton Plasma Physics Lab

The Department of Energy is shutting down a major fusion-energy project at the Princeton Plasma Physics Lab after spending nearly $100 million on its design and construction.

Continuing to assemble the National Compact Stellerator Experiment — described in an April review as substantially over budget, four years behind schedule, and facing continued uncertainties — would put “the future of research at PPPL in unnecessary peril,” said Raymond L. Orbach, under secretary for science at the U.S. Department of Energy.

Instead, Orbach said, the lab should focus on enhancing another fusion experiment that has been operating successfully since 1999 — the National Spherical Torus Experiment. The spherical torus is a device to study the physics principles of spherically shaped plasmas — hot ionized gases confined in a magnetic field in which nuclear fusion will occur.

“Proposed upgrades for the spherical torus experiment at PPPL can keep this facility at the forefront of fusion science research in the world well into the future,” Orbach said in a May 22 statement. He stressed the DOE’s “strong commitment to the future of PPPL.” The lab dates back to 1951, when Professor Lyman Spitzer *38 initiated the study of fusion at Princeton.

Lab officials had hoped that the stellerator would come on line as PPPL’s flagship experiment in time to replace the spherical torus, originally scheduled to shut down after 2010. But the stellerator, designed to test a possible configuration for a fusion-power reactor, fell victim to a tight federal research budget and to the complexities of its irregular shape — its 18 coils are described as among the most complicated electromagnets ever designed.

The stellerator project accounts for $14 million of the lab’s $75 million annual budget; about 40 scientists, engineers, and technicians are directly involved with it. Princeton officials are hoping that for the next fiscal year, at least some of that money will be reallocated to the spherical torus — both in allowing the experiment to be run for more weeks during the year, and to begin the proposed upgrades.

A.J. Stewart Smith, dean for research, said enhancements to the spherical torus could take three years to design and build at a cost “in the tens of millions of dollars.” But work to double the device’s current and magnetic field would increase its productivity four-fold, he said.