PPPL-designed coils arrive in Germany for fusion experiment

PPPL-designed coils arrive in Germany for fusion experiment

Engineers at the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) have designed and delivered to Germany two critical components for a major device to develop fusion power.

The "trim coil" components, each the size of a barn door, are the first of five installments of one of the largest hardware collaborations that PPPL has conducted with an international partner.

The 2,400-pound trim coils have been produced at PPPL for the Wendelstein 7-X stellarator, or W7-X, that the Max Planck Institute for Plasma Physics (IPP) is building in Greifswald, Germany. The powerful coils will fine-tune the shape of the superhot, charged gas called plasma that the W7-X will use to study conditions required for fusion when the machine begins operating in 2015. In exchange for the coils, PPPL scientists will be able to lead and carry out experiments on the W7-X.
Stellarators are one of the two major devices that scientists are using to develop fusion as a source of clean and abundant energy. The other device is the tokamak. "Stellarators offer solutions to problems facing magnetic fusion reactors that haven't been solved in any other way to date," said George "Hutch" Neilson, director of advanced projects at PPPL.

Delivery of the first trim coil on June 26 capped two years of teamwork between PPPL and IPP and a final month of intense activity. PPPL engineers Michael Mardenfeld and Steve Raftopoulos, with colleagues from IPP, traveled to coil manufacturer Everson Tesla in Nazareth, Pa., when surface imperfections appeared in the epoxy-like resin that encases the copper coil. "The stakes are fairly high," said Neilson. "Whenever you build the first of anything there are always unexpected surprises that you have to work your way through. In this case, the imperfections turned out to be nothing and were easily removed."

The five coils are to be delivered to IPP by January. "Getting the first coil out the door was very challenging," said PPPL engineer Stephen Langish, who manages the trim coil project and monitored the first one with Mardenfeld, Raftopoulos and quality assurance engineer Frank Malinowski. "We just had a very aggressive schedule."

Delivery of the first coil over the 4,300-mile sea and land route to Greifswald proved no less challenging. Workers at Everson Tesla had to crate the device standing up since it was too wide to travel on German roads without a police escort. "There was enough wood in the crate to build two backyard decks," said Greg Naumovich, the president of Everson Tesla, which is manufacturing the coils under an $800,000 contract with PPPL.  

The crate was barely within the 13-foot height ceiling for German roads when the coil arrived in Antwerp, Belgium, from Chester, Pa., and was loaded onto a flatbed truck. Planners carefully plotted the 500-mile route from Antwerp to Greifswald in northeast Germany to avoid low highway clearances. The similarly packaged second coil traveled the same route and arrived on Aug. 3.

Safe delivery of the first coil ended a period of anxious waiting in Greifswald. "I was relieved that the coil was not damaged, and also proud of the result of our teamwork with PPPL," said engineer Konrad Risse, the trim coil project leader at IPP. "This collaboration was very special because the trim coils are the first large component to be provided by another scientific laboratory."

Technicians will assemble the coils on the W7-X alongside other key parts from more than 30 companies throughout Europe. Installation of the first trim coil is scheduled in September. The coils will enable stellarator experiments to run smoothly by correcting any errors in the magnetic field that surrounds and shapes the plasma.

Back at PPPL, engineers have completed the design of five electric power supplies that will run the W7-X trim coils when the stellarator begins operating. Applied Power Systems of Hicksville, N.Y., received the contract to produce the supplies, which are to be delivered to Greifswald by August 2013.

Timely delivery of the first trim coil was a key step for the overall project. "It's an important accomplishment that puts us on target to deliver all five coils in excellent fashion," said Neilson, the PPPL director of advanced projects. "We're probably going to come in ahead of schedule and under budget."

Princeton Plasma Physics Laboratory, funded by the U.S. Department of Energy and managed by Princeton University, advances the coupled fields of fusion energy and plasma physics. Fusion is the process that powers the sun and the stars. In the interior of stars, matter is converted into energy by the fusion, or joining, of the nuclei of light atoms to form heavier elements. At PPPL, physicists use a magnetic field to confine plasma. Scientists hope eventually to use fusion energy for the generation of electricity.