Fusion energy

Princeton Plasma Physics Laboratory pursues clean and plentiful energy

By: Hilary Parker
   NSTX. NCSX. ITER. PPPL.
   The fact that the people at the Princeton Plasma Physics Laboratory like their four-letter words is quite obvious. But what do these acronyms mean? What actually goes on behind the security gates that bar the entrance to the laboratory? And does the general public have any hope of grasping what plasma physics and fusion energy are, and how they work?
   Absolutely, and especially if they listen to laboratory director Dr. Robert Goldston, who explains fusion energy as if it were a children’s story — assuming that the children in question know what atoms are …
   "You take hydrogen gas and heat it up really hot, to a temperature 10 times hotter than the surface of the sun. And when a gas is 10 times hotter than the surface of the sun, you can hold it in place with magnets," he begins.
   Dr. Goldston’s simple word choice and repetition beckon any listener to lean closer, listen harder.
   "When it gets that hot," he continues, "atoms bang into each other and you have a soup of nuclei and electrons — that’s called a plasma."
   Now for the fun part.
   "When it’s really hot, and they’re flying around really fast, they go WHAM!" Dr. Goldston says, loudly, smashing one fist into his other hand with a satisfying smack.
   "They slam together to make helium and a single energetic neutron. Then you capture the heat, boil water, make steam and use it to make electricity."
   It all sounds so simple. Essentially, two atoms fuse and release vast amounts of energy. It sounds easy enough, and would theoretically provide a clean, plentiful, and safe energy source by using the hydrogen from water as the source of fuel. So why isn’t the world powered by fusion energy already?
   Dr. Goldston explains that in order to reach this goal, the PPPL has to address three major challenges.
   "There are three balls in the air," he says. The lab must juggle the need to produce enough fusion energy (ball one) in a continuous manner (ball two), in a cost-effective way (ball three).
   To address the first requirement, PPPL is involved in ITER, which means "the way" in Latin.
   ITER is an international fusion experiment that will ultimately be based in Cadarache, France. The PPPL was recently selected to host the U.S. Project Office of the project, which involves the governments of more than one-third of the world’s population. In this capacity the PPPL will coordinate the provision of the major magnet system to control the plasma, as well as part of the surface that contains the plasma and the instrumentation to enable scientific studies.
   In 2016, when the first plasma experiments run on ITER, it will produce 500 million watts of fusion heat, a "first" by a factor of 50, according to Dr. Goldston. But the project is much more than a lot of hot plasma.
   "It’s not just a science and technology experiment," says Dr. Ned Sauthoff, project manager of the U.S. ITER Project. "It’s also an experiment in international relations. It’s an attempt to have the major nations of the world work together to solve a common problem."
   Given that it’s such a large-scale effort on all fronts, the ITER project (with its $200 million/year price tag in the United States alone), is not exactly addressing the need to provide fusion energy in the most cost-effective manner. For that, PPPL turns to NSTX — the National Spherical Torus Experiment.
   Dr. Maso Ono, NSTX project manager, explains that the scientists conducting experiments in NSTX control the plasma remotely from a control room filled with computer monitors. The reason for this remote method is the temperatures of the experiments, 10,000 times hotter than the sun. "Any object will evaporate immediately," he says with a laugh and a shrug.
   Scientists the whole world over apply to conduct experiments at NSTX. Typically they secure two or three days of run time per experiment. Experiments are carried out over the course of a year or two, and scientists analyze the data between actual runs in the plasma chamber.
   David Gates, principal research physicist with NSTX, uses computers to change the shape of the plasma inside the machine by altering the strength of the magnets that keep it in place. The computers make calculations 5,000 times each second to gauge how the plasma is reacting, and then change the strength of the magnets accordingly.
   The scientists’ ultimate quest is to find a shape of plasma that’s relatively stable but also capable of supplying ample amounts of fusion energy. The more unstable the plasma is, the more energy it takes to keep it in place — kind of like an unruly child. The plasma in NSTX is in the shape of a torus, essentially a doughnut with a very small hole in the center.
   Shape is very important when it comes to plasma. In order to address the need to supply fusion energy in a continuous fashion, the PPPL is currently constructing NCSX — the National Compact Stellarator Experiment.
   Hutch Neilson, NCSX project manager, explains a stellarator simply. "It’s a doughnut with a twist," he says. That little kink, the twist, makes it easier to supply fusion power continuously. In addition, the magnets controlling the plasma (6,000 pounds each) have a more complicated shape that makes the plasma even more stable.
   Even though they’re working at supersolar temperatures with machines worth billions of dollars amongst some of the brightest minds in the nation, the scientists at PPPL are very friendly and down-to-earth, as is the atmosphere at the lab.
   For instance, Mr. Neilson sent around an e-mail titled "A Thing of Beauty Hs Arrived" when the first of 18 6,000-pound magnets for NCSX arrived at the lab. This was after its unplanned tour through Brooklyn; the husband-and-wife team delivering the magnet got lost somewhere en route from the Midwest. No worries, though: The scientists themselves talked the couple over the Brooklyn Bridge and into town.
   "There’s remarkably little friction here," says Dr. Goldston, not even trying to make a pun. He explains that with a common mission, people work together and appreciate each others’ talents and interests. The testimony to this fact is that staff tend to stick around. Dr. Goldston and Dr. Sauthoff both came to PPPL in 1972 as graduate students, and Dr. Ono arrived the following year. Irving Zatz, a structural engineer, has been with PPPL for 25 years.
   "You find that people come here and spend most, if not all, of their career here," Mr. Zatz says.
   In her position as one of three female physicists at the lab, Dr. Cynthia Phillips has remained with the lab for 22 years. She came as a post-doc and has climbed the ranks to become a principal research physicist who also heads up a science focus group and lectures with the rank of professor at Princeton University.
   "People here respect scientific output, so if you deliver it then you get respected," she says of her status as one of the few females in a male-dominated environment. She explains that while there will always be some subtle differences between male- and female-dominated environments, her experiences at PPPL have been overwhelmingly positive.
   She cites management programs such as "Take Your Daughter to Work Day" and a collaboration with Rutgers University to expose female high school and college students to science and engineering as definite steps in the right direction, which don’t come as a surprise to her. Since the managers at PPPL have risen through the ranks they have a firm grasp on the culture and needs of the place.
   Like every workplace, the PPPL also has its jokester, Dr. Andrew Post-Zwicker, the head of the Science Education Program. It’s a perfect spot for him to share his vast knowledge of physics and joke around with students, ranging from kindergartners to undergraduates in college, who participate in the program.
   He seems to like the plasma light sabers as much as they do, if not more — and don’t even get him started about the plasma mug. Working to spread the word about fusion, Dr. Post-Zwicker likes to tie in pop culture to reach his students. "The power of the sun in the palm of your hand," he quotes Dr. Otto Octavius from "Spiderman 2" in a booming voice, as he mimes tentacles sprouting from his back.
   And then there’s the office Christmas party, and the skit. The skit is perhaps more top-secret than any of the research at the lab, to hear Patti Wieser, Information Officer at PPPL, tell it. Filled with inside jokes and physics humor, the skit makes the PPPL seem almost like your everyday office.
   But not quite. After all, they are working to provide the world with an entirely new source of energy.
   So, will it work? Will the PPPL provide the world with the energy source of the future?
   "I think it’s a sure thing we can make industrial levels of fusion energy," says Dr. Goldston. "The question is, ‘How economically competitive will it be?’ The payoff is 75 to 1, but the certainty, I don’t know …"
   One thing that’s for certain is that the people at PPPL believe in its mission and have dedicated their lives to making fusion energy a reality.
   "Everybody’s in it for the same overall goal — to develop fusion for humanity," says Dr. Goldston.