Elizabeth Paul, developer of a groundbreaking method for optimizing magnetic confinement stellarator fusion facilities, has won a Princeton University Presidential Postdoctoral Research Fellowship to advance the method at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL). Paul received her doctoral degree from the University of Maryland, College Park, in May and will join the Princeton University Department of Astrophysical Sciences under the supervision of Amitava Bhattacharjee, head of the Theory Department at PPPL and a Princeton professor of astrophysical sciences.

Stellarators, twisty alternatives to more widely used doughnut-shaped tokamaks, run without the risk of damaging disruptions that tokamaks face. Paul has developed a unique mathematical method to speed up the optimal design of the complex magnetic coils in stellarators. “I’m very honored for having been selected for this fellowship and I’m excited to be spending time at PPPL and working with Amitava,” Paul said. “My planned research fits in very nicely with current work at the Lab.”

Far-reaching research

PPPL Director Steve Cowley acknowledges the far-reaching nature of her work. “Elizabeth’s invention of a method to optimize how coils can be configured to make stellarator designs is a major breakthrough,” Cowley said. “Like many very smart ideas it wasn’t at all obvious until she invented it, and then it seemed beautifully simple. Perfect, really."

Scientists use stellarators and tokamaks to heat and confine plasma, the state of matter composed of free electrons and atomic nuclei that fuels the fusion reactions that power the sun and stars. Such devices aim to create and control fusion on Earth to provide a safe, clean and virtually limitless source of power for generating electricity.

Paul is among the 16 scholars from across academic disciplines that Princeton University has selected this year for presidential fellowships, with the goal of increasing diversity. The fellowship program, coordinated by the Office of the Dean of the Faculty with support from the Office of the President and the Office of the Provost, recognizes standout doctoral graduates from groups historically or currently underrepresented in the academy or in certain disciplines.

Paul earned her bachelor’s degree from the Princeton Department of Astrophysical Sciences before developing her mathematical method under the supervision of Maryland research scientist Matt Landreman and Professor William Dorland. Dorland, who co-advised with Landreman and Professor Tom Antonsen, noted that, "We learned a great deal from Elizabeth, which is what happens with the best graduate students – they teach us!”

Mathematical insights

Paul’s three-year fellowship, with the first two years supported by Princeton University and the third year by PPPL, will bring her mathematical insights to the laboratory. “My work will be somewhat of an extension of the work I did on my Ph.D. developing new tools for the optimization of stellarators,” she said. “The so-called adjoint methods I worked on make optimization much faster by reducing the number of required evaluations of the objective function by several orders of magnitude,” she said. “These functions quantify desirable properties for the configuration of stellarator coils.”

Paul became interested in science while in high school in Portland, Oregon, where she enjoyed research in a biomedical lab and began thinking about scientific research as a career. At Princeton she and other students made a video about plasma physics at PPPL under the supervision of Arturo Dominguez, senior program leader in the Department of Science Education. “We put together this video about the basics of fusion energy and we talked to different scientists at PPPL,” she said. “In the summer after that I got an internship at PPPL, where I worked with Sam Cohen and did some modeling for his Field Reversed Configuration device. I guess that’s how I became interested in plasma physics.”

Paul went on to teach physics as a graduate student, and co-developed an introductory document about stellarators that the 2019 Simons Foundation-PPPL summer school used. She has also done work with the Simons Collaboration on Hidden Symmetries and Fusion Energy, an international collaboration that seeks to develop a mathematical and computational framework for optimizing stellarators that Bhattacharjee of Princeton and PPPL directs.

At PPPL Paul will have the opportunity to teach and mentor graduate and undergraduate students in addition to pursuing her own research. The tools she is developing are quite general and could be used to enhance current stellarator research at the laboratory.

PPPL, on Princeton University's Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit energy.gov/science.