Developing materials for stellar performance in fusion power plants

Developing materials for stellar performance in fusion power plants
by Poornima Apte | MIT Department of Nuclear Science and Engineering
Boston MA (SPX) Mar 11, 2025

When Zoe Fisher was in fourth grade, her art teacher asked her to draw her vision of a dream job on paper. At the time, those goals changed like the flavor of the week in an ice cream shop - "zookeeper" featured prominently for a while - but Zoe immediately knew what she wanted to put down: a mad scientist.

When Fisher stumbled upon the drawing in her parents' Chicago home recently, it felt serendipitous because, by all measures, she has realized that childhood dream. The second-year doctoral student at MIT's Department of Nuclear Science and Engineering (NSE) is studying materials for fusion power plants at the Plasma Science and Fusion Center (PSFC) under the advisement of Michael Short, associate professor at NSE. Dennis Whyte, Hitachi America Professor of Engineering at NSE, serves as co-advisor.

On track to an MIT education

Growing up in Chicago, Fisher had heard her parents remarking on her reasoning abilities. When she was barely a preschooler she argued that she couldn't have been found in a purple speckled egg, as her parents claimed they had done.

Fisher didn't put together just how much she had gravitated toward science until a high school physics teacher encouraged her to apply to MIT. Passionate about both the arts and sciences, she initially worried that pursuing science would be very rigid, without room for creativity. But she knows now that exploring solutions to problems requires plenty of creative thinking.

It was a visit to MIT through the Weekend Immersion in Science and Engineering (WISE) that truly opened her eyes to the potential of an MIT education. "It just seemed like the undergraduate experience here is where you can be very unapologetically yourself. There's no fronting something you don't want to be like. There's so much authenticity compared to most other colleges I looked at," Fisher says. Once admitted, Campus Preview Weekend confirmed that she belonged. "We got to be silly and weird - a version of the Mafia game was a hit - and I was like, 'These are my people,'" Fisher laughs.

Pursuing fusion at NSE

Before she officially started as a first-year in 2018, Fisher enrolled in the Freshman Pre-Orientation Program (FPOP), which starts a week before orientation starts. Each FPOP zooms into one field. "I'd applied to the nuclear one simply because it sounded cool and I didn't know anything about it," Fisher says. She was intrigued right away.

"They really got me with that 'star in a bottle' line," she laughs. (The quest for commercial fusion is to create the energy equivalent of a star in a bottle). Excited by a talk by Zachary Hartwig, Robert N. Noyce Career Development Professor at NSE, Fisher asked if she could work on fusion as an undergraduate as part of an Undergraduate Research Opportunities Program (UROP) project. She started with modeling solders for power plants and was hooked.

When Fisher requested more experimental work, Hartwig put her in touch with Research Scientist David Fischer at the Plasma Science and Fusion Center (PSFC). Fisher eventually moved on to explore superconductors, which eventually morphed into research for her master's thesis.

For her doctoral research, Fisher is extending her master's work to explore defects in ceramics, specifically in alumina (aluminum oxide). Sapphire coatings are the single-crystal equivalent of alumina, an insulator being explored for use in fusion power plants. "I eventually want to figure out what types of charge defects form in ceramics during radiation damage so we can ultimately engineer radiation-resistant sapphire," Fisher says.

When you introduce a material in a fusion power plant, stray high-energy neutrons born from the plasma can collide and fundamentally reorder the lattice, which is likely to change a range of thermal, electrical, and structural properties.

"Think of a scaffolding outside a building, with each one of those joints as a different atom that holds your material in place. If you go in and you pull a joint out, there's a chance that you pulled out a joint that wasn't structurally sound, in which case everything would be fine. But there's also a chance that you pull a joint out and everything alters. And [such unpredictability] is a problem," Fisher says. "We need to be able to account for exactly how these neutrons are going to alter the lattice property," Fisher says, and it's one of the topics her research explores.

The studies, in turn, can function as a jumping-off point for irradiating superconductors. The goals are two-fold: "I want to figure out how I can make an industry-usable ceramic you can use to insulate the inside of a fusion power plant, and then also figure out if I can take this information that I'm getting with ceramics and make it superconductor-relevant," Fisher says.

"Superconductors are the electromagnets we will use to contain the plasma inside fusion power plants. However, they prove pretty difficult to study. Since they are also ceramic, you can draw a lot of parallels between alumina and yttrium barium copper oxide (YBCO), the specific superconductor we use," she adds. Fisher is also excited about the many experiments she performs using a particle accelerator, one of which involves measuring exactly how surface thermal properties change during radiation.

Sailing new paths

It's not just her research that Fisher loves. As an undergrad, and during her master's, she was on the varsity sailing team. "I worked my way into sailing with literal Olympians, I did not see that coming," she says. Fisher participates in Chicago's Race to Mackinac and the Melges 15 Series every chance she gets. Of all the types of boats she has sailed, she prefers dinghy sailing the most. "It's more physical, you have to throw yourself around a lot and there's this immediate cause and effect, which I like," Fisher says. She also teaches sailing lessons in the summer at MIT's Sailing Pavilion - you can find her on a small motorboat, issuing orders through a speaker.

Teaching has figured prominently throughout Fisher's time at MIT. Through MISTI, Fisher has taught high school classes in Germany and a radiation and materials class in Armenia in her senior year. She was delighted by the food and culture in Armenia and by how excited people were to learn new ideas. Her love of teaching continues, as she has reached out to high schools in the Boston area. "I like talking to groups and getting them excited about fusion, or even maybe just the concept of attending graduate school," Fisher says, adding that teaching the ropes of an experiment one-on-one is "one of the most rewarding things."

She also learned the value of resilience and quick thinking on various other MISTI trips. Despite her love of travel, Fisher has had a few harrowing experiences with tough situations and plans falling through at the last minute. It's when she tells herself, "Well, the only thing that you're gonna do is you're gonna keep doing what you wanted to do."

That eyes-on-the-prize focus has stood Fisher in good stead, and continues to serve her well in her research today.