Of hohlraums and plasmas and machines called “Z”
PPPL Director Stewart Prager described a host of scientific activities at the Lab during a talk at the annual Fusion Power Associates (FPA) meeting held in Washington, D.C. Steve Dean, the executive director of FPA, can be seen to his left. (Photo credit: Kitta MacPherson, PPPL Office of Communications)
By Kitta MacPherson
WASHINGTON, D.C. – What happens when the forces of fusion gather?
At the annual meeting of the Fusion Power Associates, held at the tony Capitol Hill Club in the shadow of the U.S. Capitol, there’s lots of talk about “plasmas” and “hohlraums” and of devices called stellarators and other machines with names like “Z.”
Starting yesterday and continuing through today, the leaders of fusion energy research in the U.S. from U.S. Department of Energy-funded laboratories, as well as from industry and publicly funded university programs, have been and will continue to line up and present, in rigorously timed 20-minute-long segments, the state of their art. Differences in approaches to fusion from inertial confinement where pellets are zapped by lasers to magnetic confinement where a superhot gas is corked in a magnetic bottle are described. As competitive as the programs may be, all are regarded here as being under the aegis of fusion–part of the ecumenical approach of Steve Dean, the founder and executive director of the sponsoring group, the Fusion Power Associates.
The purpose of FPA, a non-profit foundation based in Gaithersburg, Md., is, according to its website, to “ensure the timely development and acceptance of fusion as a socially, environmentally, and economically attractive source of energy.” The meetings are designed to showcase management-level scientists and their technical achievements.
In the long narrow, federal style Eisenhower Room, an observer in the space of several minutes can hear a full range of approaches to fusion from some of its best minds. Attendees can hear Mike Dunne, a leading scientist at the National Ignition Facility based at Lawrence Livermore National Laboratory in California, describe scientific advances in inertial fusion at the facility, pointing to diagrams showing cylindrical capsules called “hohlraums” that hold fusion fuel capsules. One can then listen to Stewart Prager, director of the Princeton Plasma Physics Laboratory, convey elements of progress in magnetic fusion. The Princeton lab is focusing on areas with breakthrough potential where the U.S. can lead, he said. And lest anyone think that PPPL is overly focused on a doughnut-shaped fusion reactor configuration known as a tokamak, Prager indicated his commitment to also support another configuration known as a stellarator. “We believe that stellarators are not a luxury item, we believe they are essential for fusion,” he said.
Observers at the meeting also can get a taste of the international.
Ned Sauthoff, director of the U.S. ITER program, talked about the importance of scientific research being conducted now to benefit ITER, a mammoth experimental fusion vessel under construction in Cadarache, France. “The science of ITER is happening now,” he said. “In order for it to succeed, you have to have a strong program that is related to things like burning plasmas.” The goal of ITER is to achieve 500 megawatts of fusion power. The giant tokamak is being designed to demonstrate the scientific and technological feasibility and safety features of fusion energy, Sauthoff said.
Tight budgets for domestic programs have leaders such as Miklos Porkolab, director of MIT’s Plasma Science Fusion Center, expressing concerns. “Vigorous research in the next decade is necessary on existing tokamak facilities with upgrades in heating and current drive power as well as advanced plasma diagnostics and tungsten plasma-facing components,” he said, adding that much physics remains to be explored on existing tokamaks in order to optimize ITER’s operation. The largest U.S. experimental magnetic fusion devices–at MIT, PPPL, and General Atomics–are complementary, he noted, and need sustained support.
In his presentation on fusion experiments at Los Alamos National Laboratory, Glen Wurden said he is worried about the impact of cuts to the domestic fusion program, especially in light of growing ITER commitments, and the survivability of the U.S. plasma physics and fusion research enterprise should there be additional cuts in future years. “We are dangerously approaching the tipping point,” he said.
Mark Herrmann, a physicist at Sandia National Laboratory, who was recognized for his research with an award from FPA, spoke with excitement about his work on a 10,000 square-foot experimental fusion device known as “Z”. “You have to be an optimist to be a fusion scientist,” he said with a smile.