DOE’s Ed Synakowski traces key discoveries in the quest for fusion energy
The path to creating sustainable fusion energy as a clean, abundant and affordable source of electric energy has been filled with “aha moments” that have led to a point in history when the international fusion experiment, ITER, is poised to produce more fusion energy than it uses when it is completed in 15 to 20 years, said Ed Synakowski, associate director of Science for Fusion Energy Sciences at the U.S. Department of Energy (DOE).
Speaking at a Ronald E. Hatcher Science on Saturday lecture on March 5 at the DOE’s Princeton Plasma Physics Laboratory (PPPL), Synakowski traced the discoveries that have led to this moment as well as his own personal journey as a plasma physicist. Synakowski was a researcher on PPPL’s Tokamak Fusion Test Reactor from 1988 through its closure in 1997. He was head of Research and deputy program director of the National Spherical Torus Experiment at PPPL from 1998 to 2005.
“Getting there, if you think about nuclear fusion, is going to take some moments of discovery, some ‘aha’ moments,” Synakowski said in his talk, “Reimagining the Possible: Scientific Transformations Shaping the Path Towards Fusion Energy.” “We’re taking the process that powers the sun and the stars and bringing it to earth for the benefit of mankind.”
Under a fusion power roadmap developed by European scientists, the next step after ITER would be to build fusion power plants that could begin generating electricity as early as the middle of this century, Synakowski said. Fusion energy would supplement other green sources of electricity, such as wind and power, which have great potential but face the challenge not only of relying on the weather but of storing energy, Synakowski said. “Any robust clean energy infrastructure will benefit greatly from a mix that includes renewables as well as something like fusion,” he said. “You need something that’s clean and has the potential of stable, reliable electric power,” he said.
Wendelstein 7-X a sign of progress
Another sign of progress on the road to fusion energy was the Feb. 3 celebration of the first hydrogen plasma at the Wendelstein 7-X stellarator in Greifswald, Germany, Synakowski said. He attended the event along with A.J. Stewart Smith, Princeton University’s vice-president for PPPL, and several PPPL researchers. Synakowski noted that PPPL leads the U.S. collaboration with W7-X scientists, which is vital because the U.S. does not have a stellarator of the same scale as W7-X .
Synakowski explored his own roots as a scientist, culminating in his current position with the Office of Fusion Energy Science, which supports research to develop the scientific basis for fusion energy, and serves as a leading steward of plasma science. The FES has a budget of over $400 million and oversees research at national laboratories, universities, and in private industry. Synakowski was previously the Fusion Energy Program leader and the deputy division leader at large of the Physics Division at the Lawrence Livermore National Laboratory. An American Physical Society and Institute of Physics fellow, he has written more than 160 publications. He received a Ph.D. in physics from the University of Texas at Austin and a bachelor’s degree from Johns Hopkins University.
Synakowski said his own journey to joining the quest for fusion energy began as a child when he was fascinated by space. He recalled his feeling of elation as a boy when he was able to identify Saturn using his home telescope. “My career in the sciences has been an effort to capture that kind of moment because it’s so powerful and uplifting,” he said. “The field, I think, has had many such moments.”
Fusion energy is based on the same process that takes place in the sun, where gravity holds together the hot ionized gas called a plasma and nuclei of hydrogen collide together often enough that they occasionally overcome forces keeping them apart, called the Coulomb forces, to fuse together and create a burst of energy, Synakowski explained.
Fusion energy uses two isotopes of hydrogen: deuterium, which can be extracted from seawater, and tritium, a radioactive isotope that is not naturally available but can be produced in a fusion reactor. Unlike many other forms of energy, it takes a small amount of fuel to produce a large amount of energy, Synakowski said. A power plant that produces 1,000 megawatts of energy consumes 9,000 tons of coal a day and emits 30,000 tons of carbon dioxide, the most common greenhouse gas linked to climate change. A fusion power plant producing the same amount of energy would produce just 4 pounds of helium as a byproduct. And compared to the byproducts of nuclear plants, which remain radioactive for thousands of years, the small amount of radioactive material produced in fusion reactions would remain radioactive for tens of years, Synakowski said.
Synakowski noted that humankind’s energy consumption has increased over the centuries as people’s lifespan has increased. In the past 160 years, U.S. life expectancy has doubled from 40 to 80, Synakowski said. That has been partly due to the availability of energy, he said, and has caused political instability as developing countries strive to obtain a plentiful energy source that will improve their people’s quality of life. The increased lifespan has also required additional energy. Meanwhile, the source of energy has also evolved from wood to coal, to petroleum, natural gas and nuclear sources of electric power. “Energy drives a quality of life that isn’t going away,” he said.
Lyman Spitzer and the first fusion energy device
Synakowski traced the roots of fusion energy to Princeton astrophysicist and PPPL founder Lyman Spitzer who led a classified program called “Project Matterhorn” in the 1950s and was the first to come up with the idea of creating fusion energy in a device he called a “stellarator.” Spitzer’s device had the same basic elements of modern fusion devices, Synakowski said. It used an ionized gas called a plasma for fuel and had magnets on the outside to create a magnetic field to contain the plasma and keep it away from the walls. Spitzer believed that if the plasma could be heated to 200 million degrees Centigrade, he could create a fusion reaction.
But the stellarator was not the only type of fusion experiment in the world. The British created a device called a “pinch” and the Russians invented a doughnut-shaped device called a “tokamak.” The Russians announced they had achieved an electron temperature of up to 20 million degrees Centigrade in the plasmas in their fusion experiments and the results convinced many researchers around the world that the tokamak was a better way to confine the plasma to create fusion energy. After the stellarator produced disappointing results in the 1950s and 1960s, many laboratories worldwide, including the Princeton Plasma Physics Laboratory, which was renamed in 1961, followed the example of the Russians.
Synakowski was a researcher at PPPL during some of the “aha” moments at PPPL’s Tokamak Fusion Test Reactor (TFTR), which operated from 1982 to 1997 and was then the biggest tokamak in the U.S. and the third biggest in the world. Synakowski showed the audience a picture of himself, along with Mike Zarnstorff, now PPPL’s deputy director of research, Richard Hawryluk, now the had of ITER and Tokamaks at PPPL; and several other scientists in the control room of TFTR on Dec. 9, 1993. That’s when the facility achieved a world-record 6.3 million watts of fusion power with a 50-50 mix of deuterium and tritium. In June of 1994, TFTR would generate headlines worldwide when it produced 10.7 million watts of fusion power, Synakowski said.
Meanwhile, the development of computers over the decades made it possible for physicists to more accurately predict experimental results, Synakowski said. That has made theoretical physics and computing essential to fusion research. For example, there was widespread concern based on work by theorists in the early 1970s that certain “drift instabilities” in fusion experiments would cool the plasma and prevent tokamaks from reaching the conditions necessary for fusion to occur. Later in the 1970s, theorists used new analyses and some of the first computational plasma physics studies to show that the picture was much less bleak than originally thought. Experiments at PPPL were central to helping to settle the question. Research on the Princeton Large Torus found there was no evidence of a universal instability, and that temperatures close to those required for a reactor could be generated efficiently. This kind of theory-experiment comparison has evolved over the decades, and now theoretical physicists like PPPL’s C.S. Chang use complex computer simulations to predict fluctuations in the plasma that can inhibit fusion reactions, Synakowski said. “These simulations are used to inform research in a way previously unimagined,” he said.
Synakowski credited Zarnstorff with another “aha” moment -- “transformational research” in which Zarnstorff identified a phenomenon called a “bootstrap current.” The plasma generates the bootstrap current itself, thus reducing the need for more power to produce the external plasma currents necessary to heat and confine the plasma.
Such discoveries have propelled fusion research forward and have captured his imagination and that of other scientists like him, Synakowski. But Synakowski said he has not only been drawn by the science of fusion energy but also by the pure beauty of plasma found in phenomenon like the Northern Lights, which he saw several years ago. And most of all, he has been captivated by the potential of fusion energy to change the world. “I feel most fortunate to have been a part of this journey, to be able to witness it, to be able to work in this field and to allow it to stimulate additional moments of discovery for me,” he said. “I can’t think of another field of science that is more compelling, both for the beauty of it and the practical import of it.”
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