Department of Energy fellow pushes the boundaries for clean energy through nuclear fusion

Growing up, Rebecca Masline, Ph.D., was inspired by the popular television program “MythBusters” to create her own science experiments with her neighbors. Her parents encouraged her and instilled in her the importance of helping others. Later, Masline developed an interest in creating things for the water and power industry. After transferring to the University of California, San Diego, to study engineering, Masline met a professor in an elective course on renewable and nuclear energy well-known for their contributions to nuclear fusion, the “holy grail” of clean energy solutions. When soliciting advice on her current career paths of wastewater management or fission nuclear power plants, he instead offered Masline the opportunity to help with his research in plasma physics and nuclear fusion as a Ph.D. student. Masline studied under his guidance for both her master’s and Ph.D. in mechanical engineering with a focus on plasma physics.

While looking for research opportunities, Masline discovered the U.S. Department of Energy (DOE) Fusion Energy Sciences Postdoctoral Research Program through the Oak Ridge Institute for Science and Education (ORISE). The program offered an opportunity to conduct research on SPARC, a demonstration device aimed at fusing deuterium and tritium and exceeding breakeven plasma conditions to create and confine plasmas that produce more power by fusion reactions than absorbed from the external heating systems. Masline applied and was accepted to participate in the program.

The Fusion Energy Sciences Postdoctoral Research Program offers recent doctoral degree recipients the opportunity to conduct research in the DOE fusion energy sciences research programs. Participants acquire experience and training in areas of fusion and plasma science and technology, interact with outstanding scientists and engineers and have access to advanced equipment and facilities.

Being an ORISE fellow is so unique and I feel like I have been able to develop considerably as a researcher and figure out how to conceptualize projects. I’m really grateful to have had such a unique experience, especially this early in my career.

With the Boundary Modelings Group at the Plasma Science and Fusion Center at the Massachusetts Institute of Technology, Masline is researching fuel efficiency and helium enrichment in exhaust systems in nuclear fusion devices using high-fidelity computer simulations. Recreating fusion, a process that powers the sun and stars, on Earth through magnetic confinement of ionized hydrogenic particles would produce usable energy and one atom of helium ash as a byproduct. Such Future Fusion Pilot Plants would use deuterium and one tritium atom, isotopes of hydrogen, as the fuel for the fusion reaction. Currently, the team wants to achieve efficiency with the process as naturally occurring tritium is extremely rare and would have to be bred on-site using a special blanket technology.

“Efficiency in fusion reactions is usually characterized as an efficiency for a discrete event, like one reaction at a time, which isn’t super useful for a power plant, which is supposed to be operated at steady state,” she said. “What we’re trying to do with this project is to develop a metric by which we can quantify fuel usage in fusion power plants at steady state, and the way that we’re aiming to do this is by looking at the concentration of ash in the exhaust stream – that helium byproduct from the fusion of two hydrogenic particles.”

Masline uses computer simulations to study the physics of plasma exhaust in nuclear fusion devices called the “edge plasma,” which is the plasma on the periphery of the device between the core plasma where all the fusion reactions happen and the walls of the vessel that confines the fuel. Since the exhaust can cause significant damage to the walls of the vessel, it’s important that it’s controlled to avoid contaminating the fragile core plasma or destroying the confinement device.

“The physics of the edge plasma involves many complex, highly intertwined atomic, molecular and radiative processes with multi-scale transport mechanisms, making the edge plasma a very exciting, yet often poorly understood, problem that is essential to the mission of achieving controlled nuclear fusion on earth,” she said. “Ultimately, my research contributes to a decades-long, international quest to achieve controlled nuclear fusion on earth, which could one day provide a carbon-free, essentially unlimited source of energy.”

As an early bird, a typical day for Masline starts off with the very important step for many, making a coffee. Masline moves onto stopping her simulation runs and pulling data from the cluster to see how her simulations are evolving and determine any changes needed. Through this, Masline is looking for the simulations to satisfy certain constraints that the team is aiming for. Next, Masline writes postprocessing or diagnostic scripts to analyze the data. All throughout, she looks for any bugs, documents her findings and presents them to the team as an update and a chance to receive feedback. The team hopes to publish their research in the journal Nuclear Fusion in 2025 as a follow-up to an experiment published 30 years ago.

Alongside her research, Masline is a co-administrator of the largest online network of young professionals in the field of plasma physics. As a graduate student during the COVID-19 pandemic, Masline and her best friend started a Facebook page for their friends to post to as a way to uplift everyone and their studies. The group has now turned into a space for people to ask questions, get advice, network and spread some encouragement.

After the completion of her fellowship, Masline wants to continue her current focus as a research scientist.

“Being an ORISE fellow is so unique and I feel like I have been able to develop considerably as a researcher and figure out how to conceptualize projects,” Masline said. “I’m really grateful to have had such a unique experience, especially this early in my career.”

The Fusion Energy Sciences Postdoctoral Research Program is funded by and administered through the U.S. Department of Energy’s (DOE) Oak Ridge Institute for Science and Education (ORISE). ORISE is managed for DOE by ORAU.