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      in Environment

      High-energy and hungry for the hardest problems

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      A high school track star and valedictorian, Anne White has always relished moving fast and clearing high hurdles. Since joining the Department of Nuclear Science and Engineering (NSE) in 2009 she has produced path-breaking fusion research, helped attract a more diverse cohort of students and scholars into the discipline, and, during a worldwide pandemic, assumed the role of department head as well as co-lead of an Institute-wide initiative to address climate change. For her exceptional leadership, innovation, and accomplishments in education and research, White was named the School of Engineering Distinguished Professor of Engineering in July 2020.

      But White declares little interest in recognition or promotions. “I don’t care about all that stuff,” she says. She’s in the race for much bigger stakes. “I want to find ways to save the world with nuclear,” she says.

      Tackling turbulence

      It was this goal that drew White to MIT. Her research, honed during graduate studies at the University of California at Los Angeles, involved developing a detailed understanding of conditions inside fusion devices, and resolving issues critical to realizing the vision of fusion energy — a carbon-free, nearly limitless source of power generated by 150-million-degree plasma.

      Harnessing this superheated, gaseous form of matter requires a special donut-shaped device called a tokamak, which contains the plasma within magnetic fields. When White entered fusion around the turn of the millennium, models of plasma behavior in tokamaks didn’t reliably match observed or experimental conditions. She was determined to change that picture, working with MIT’s state-of-the-art research tokamak, Alcator C-Mod.

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      Alcator C-Mod Tokamak Tour

      White believed solving the fusion puzzle meant getting a handle on plasma turbulence — the process by which charged atomic particles, breaking out of magnetic confinement, transport heat from the core to the cool edges of the tokamak. Although researchers knew that fusion energy depends on containing and controlling the heat of plasma reactions, White recalls that when she began grad school, “it was not widely accepted that turbulence was important, and that it was central to heat transport. She “felt it was critical to compare experimental measurements to first principles physics models, so we could demonstrate the significance of turbulence and give tokamak models better predictive ability.”

      In a series of groundbreaking studies, White’s team created the tools for measuring turbulence in different conditions, and developed computational models that could account for variations in turbulence, all validated by experiments. She was one of the first fusion scientists both to perform experiments and conduct simulations. “We lived in the domain between these two worlds,” she says.

      White’s turbulence models opened up approaches for managing turbulence and maximizing tokamak performance, paving the way for net-energy fusion energy devices, including ITER, the world’s largest fusion experiment, and SPARC, a compact, high-magnetic-field tokamak, a collaboration between MIT’s Plasma Science and Fusion Center and Commonwealth Fusion Systems.

      Laser-focused on turbulence

      Growing up in the desert city of Yuma, Arizona, White spent her free time outdoors, hiking and camping. “I was always in the space of protecting the environment,” she says. The daughter of two lawyers who taught her “to argue quickly and efficiently,” she excelled in math and physics in high school. Awarded a full ride at the University of Arizona, she was intent on a path in science, one where she could tackle problems like global warming, as it was known then. Physics seemed like the natural concentration for her.

      But there was unexpected pushback. The physics advisor believed her physics grades were lackluster. “I said, ‘Who cares what this guy thinks; I’ll take physics classes anyway,’” recalls White. Being tenacious and “thick skinned,” says White, turned out to be life-altering. “I took nuclear physics, which opened my eyes to fission, which then set me off on a path of understanding nuclear power and advanced nuclear systems,” she says. Math classes introduced her to chaotic systems, and she decided she wanted to study turbulence. Then, at a Society of Physics Students meeting White says she attended for the free food, she learned about fusion.

      “I realized this was what I wanted to do,” says White. “I became totally laser focused on turbulence and tokamaks.”

      At UCLA, she began to develop instruments and methods for measuring and modeling plasma turbulence, working on three different fusion research reactors, and earning fellowships from the Department of Energy (DOE) during her graduate and post-graduate years in fusion energy science. At MIT, she received a DOE Early Career Award that enabled her to build a research team that she now considers her “legacy.”

      As she expanded her research portfolio, White was also intent on incorporating fusion into the NSE curriculum at the undergraduate and graduate level, and more broadly, on making NSE a destination for students concerned about climate change. In recognition of her efforts, she received the 2014 Junior Bose Teaching Award. She also helped design the EdX course, Nuclear Engineering: Science, Systems and Society, introducing thousands of online learners to the potential of the field. “I have to be in the classroom,” she says. “I have to be with students, interacting, and sharing knowledge and lines of inquiry with them.”

      But even as she deepened her engagement with teaching and with her fusion research, which was helping spur development of new fusion energy technologies, White could not resist leaping into a consequential new undertaking: chairing the department. “It sounds cheesy, but I did it for my kid,” she says. “I can be helpful working on fusion, but I thought, what if I can help more by enabling other people across all areas of nuclear? This department gave me so much, I wanted to give back.”

      Although the pandemic struck just months after she stepped into the role in 2019, White propelled the department toward a new strategic plan. “It captures all the urgency and passion of the faculty, and is attractive to new students, with more undergraduates enrolling and more graduate students applying,” she says. White sees the department advancing the broader goals of the field, “articulating why nuclear is fundamentally important across many dimensions for carbon-free electricity and generation.” This means getting students involved in advanced fission technologies such as nuclear batteries and small modular reactors, as well as giving them an education in fusion that will help catalyze a nascent energy industry.

      Restless for a challenge

      White feels she’s still growing into the leadership role. “I’m really enthusiastic and sometimes too intense for people, so I have to dial it back during challenging conversations,” she says. She recently completed a Harvard Business School course on leadership.

      As the recently named co-chair of MIT’s Climate Nucleus (along with Professor Noelle Selin), charged with overseeing MIT’s campus initiatives around climate change, White says she draws on a repertoire of skills that come naturally to her: listening carefully, building consensus, and seeing value in the diversity of opinion. She is optimistic about mobilizing the Institute around goals to lower MIT’s carbon footprint, “using the entire campus as a research lab,” she says.

      In the midst of this push, White continues to advance projects of concern to her, such as making nuclear physics education more accessible. She developed an in-class module involving a simple particle detector for measuring background radiation. “Any high school or university student could build this experiment in 10 minutes and see alpha particle clusters and muons,” she says.

      White is also planning to host “Rising Stars,” an international conference intended to help underrepresented groups break barriers to entry in the field of nuclear science and engineering. “Grand intellectual challenges like saving the world appeal to all genders and backgrounds,” she says.

      These projects, her departmental and institutional duties, and most recently a new job chairing DOE’s Fusion Energy Sciences Advisory Committee leave her precious little time for a life outside work. But she makes time for walks and backpacking with her husband and toddler son, and reading the latest books by female faculty colleagues, such as “The New Breed,” by Media Lab robotics researcher Kate Darling, and “When People Want Punishment,” by Lily Tsai, Ford Professor of Political Science. “There are so many things I don’t know and want to understand,” says White.

      Yet even at leisure, White doesn’t slow down. “It’s restlessness: I love to learn, and anytime someone says a problem is hard, or impossible, I want to tackle it,” she says. There’s no time off, she believes, when the goal is “solving climate change and amplifying the work of other people trying to solve it.” More

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      in Energy

      Bridging careers in aerospace manufacturing and fusion energy, with a focus on intentional inclusion

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      “A big theme of my life has been focusing on intentional inclusion and how I can create environments where people can really bring their whole authentic selves to work,” says Joy Dunn ’08. As the vice president of operations at Commonwealth Fusion Systems, an MIT spinout working to achieve commercial fusion energy, Dunn looks for solutions to the world’s greatest climate challenges — while creating an open and equitable work environment where everyone can succeed.

      This theme has been cultivated throughout her professional and personal life, including as a Young Global Leader at the World Economic Forum and as a board member at Out for Undergrad, an organization that works with LGBTQ+ college students to help them achieve their personal and professional goals. Through her careers both in aerospace and energy, Dunn has striven to instill a sense of equity and inclusion from the inside out.

      Developing a love for space

      Dunn’s childhood was shaped by space. “I was really inspired as a kid to be an astronaut,” she says, “and for me that never stopped.” Dunn’s parents — both of whom had careers in the aerospace industry — encouraged her from an early age to pursue her interests, from building model rockets to visiting the National Air and Space Museum to attending space camp. A large inspiration for this passion arose when she received a signed photo from Sally Ride — the first American woman in space — that read, “To Joy, reach for the stars.”

      As her interests continued to grow in middle school, she and her mom looked to see what it would take to become an astronaut, asking questions such as “what are the common career paths?” and “what schools did astronauts typically go to?” They quickly found that MIT was at the top of that list, and by seventh grade, Dunn had set her sights on the Institute. 

      After years of hard work, Dunn entered MIT in fall 2004 with a major in aeronautical and astronautical engineering (AeroAstro). At MIT, she remained fully committed to her passion while also expanding into other activities such as varsity softball, the MIT Undergraduate Association, and the Alpha Chi Omega sorority.

      One of the highlights of Dunn’s college career was Unified Engineering, a year-long course required for all AeroAstro majors that provides a foundational knowledge of aerospace engineering — culminating in a team competition where students design and build remote-controlled planes to be pitted against each other. “My team actually got first place, which was very exciting,” she recalls. “And I honestly give a lot of that credit to our pilot. He did a very good job of not crashing!” In fact, that pilot was Warren Hoburg ’08, a former assistant professor in AeroAstro and current NASA astronaut training for a mission on the International Space Station.

      Pursuing her passion at SpaceX

      Dunn’s undergraduate experience culminated with an internship at the aerospace manufacturing company SpaceX in summer 2008. “It was by far my favorite internship of the ones that I had in college. I got to work on really hands-on projects and had the same amount of responsibility as a full-time employee,” she says.

      By the end of the internship, she was hired as a propulsion development engineer for the Dragon spacecraft, where she helped to build the thrusters for the first Dragon mission. Eventually, she transferred to the role of manufacturing engineer. “A lot of what I’ve done in my life is building things and looking for process improvements,” so it was a natural fit. From there, she rose through the ranks, eventually becoming the senior manager of spacecraft manufacturing engineering, where she oversaw all the manufacturing, test, and integration engineers working on Dragon. “It was pretty incredible to go from building thrusters to building the whole vehicle,” she says.

      During her tenure, Dunn also co-founded SpaceX’s Women’s Network and its LGBT affinity group, Out and Allied. “It was about providing spaces for employees to get together and provide a sense of community,” she says. Through these groups, she helped start mentorship and community outreach programs, as well as helped grow the pipeline of women in leadership roles for the company.

      In spite of all her successes at SpaceX, she couldn’t help but think about what came next. “I had been at SpaceX for almost a decade and had these thoughts of, ‘do I want to do another tour of duty or look at doing something else?’ The main criteria I set for myself was to do something that is equally or more world-changing than SpaceX.”

      A pivot to fusion

      It was at this time in 2018 that Dunn received an email from a former mentor asking if she had heard about a fusion energy startup called Commonwealth Fusion Systems (CFS) that worked with the MIT Plasma Science and Fusion Center. “I didn’t know much about fusion at all,” she says. “I had heard about it as a science project that was still many, many years away as a viable energy source.”

      After learning more about the technology and company, “I was just like, ‘holy cow, this has the potential to be even more world-changing than what SpaceX is doing.’” She adds, “I decided that I wanted to spend my time and brainpower focusing on cleaning up the planet instead of getting off it.”

      After connecting with CFS CEO Bob Mumgaard SM ’15, PhD ’15, Dunn joined the company and returned to Cambridge as the head of manufacturing. While moving from the aerospace industry to fusion energy was a large shift, she said her first project — building a fusion-relevant, high-temperature superconducting magnet capable of achieving 20 tesla — tied back into her life of being a builder who likes to get her hands on things.

      Over the course of two years, she oversaw the production and scaling of the magnet manufacturing process. When she first came in, the magnets were being constructed in a time-consuming and manual way. “One of the things I’m most proud of from this project is teaching MIT research scientists how to think like manufacturing engineers,” she says. “It was a great symbiotic relationship. The MIT folks taught us the physics and science behind the magnets, and we came in to figure out how to make them into a more manufacturable product.”

      In September 2021, CFS tested this high-temperature superconducting magnet and achieved its goal of 20 tesla. This was a pivotal moment for the company that brought it one step closer to achieving its goal of producing net-positive fusion power. Now, CFS has begun work on a new campus in Devens, Massachusetts, to house their manufacturing operations and SPARC fusion device. Dunn plays a pivotal role in this expansion as well. In March 2021, she was promoted to the head of operations, which expanded her responsibilities beyond managing manufacturing to include facilities, construction, safety, and quality. “It’s been incredible to watch the campus grow from a pile of dirt … into full buildings.”

      In addition to the groundbreaking work, Dunn highlights the culture of inclusiveness as something that makes CFS stand apart to her. “One of the main reasons that drew me to CFS was hearing from the company founders about their thoughts on diversity, equity, and inclusion, and how they wanted to make that a key focus for their company. That’s been so important in my career, and I’m really excited to see how much that’s valued at CFS.” The company has carried this out through programs such as Fusion Inclusion, an initiative that aims to build a strong and inclusive community from the inside out.

      Dunn stresses “the impact that fusion can have on our world and for addressing issues of environmental injustice through an equitable distribution of power and electricity.” Adding, “That’s a huge lever that we have. I’m excited to watch CFS grow and for us to make a really positive impact on the world in that way.”

      This article appears in the Spring 2022 issue of Energy Futures, the magazine of the MIT Energy Initiative. More

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      in Energy

      Solving a longstanding conundrum in heat transfer

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      It is a problem that has beguiled scientists for a century. But, buoyed by a $625,000 Distinguished Early Career Award from the U.S. Department of Energy (DoE), Matteo Bucci, an associate professor in the Department of Nuclear Science and Engineering (NSE), hopes to be close to an answer.

      Tackling the boiling crisis

      Whether you’re heating a pot of water for pasta or are designing nuclear reactors, one phenomenon — boiling — is vital for efficient execution of both processes.

      “Boiling is a very effective heat transfer mechanism; it’s the way to remove large amounts of heat from the surface, which is why it is used in many high-power density applications,” Bucci says. An example use case: nuclear reactors.

      To the layperson, boiling appears simple — bubbles form and burst, removing heat. But what if so many bubbles form and coalesce that they form a band of vapor that prevents further heat transfer? Such a problem is a known entity and is labeled the boiling crisis. It would lead to runaway heat, and a failure of fuel rods in nuclear reactors. So “understanding and determining under which conditions the boiling crisis is likely to happen is critical to designing more efficient and cost-competitive nuclear reactors,” Bucci says.

      Early work on the boiling crisis dates back nearly a century ago, to 1926. And while much work has been done, “it is clear that we haven’t found an answer,” Bucci says. The boiling crisis remains a challenge because while models abound, the measurement of related phenomena to prove or disprove these models has been difficult. “[Boiling] is a process that happens on a very, very small length scale and over very, very short times,” Bucci says. “We are not able to observe it at the level of detail necessary to understand what really happens and validate hypotheses.”

      But, over the past few years, Bucci and his team have been developing diagnostics that can measure the phenomena related to boiling and thereby provide much-needed answers to a classic problem. Diagnostics are anchored in infrared thermometry and a technique using visible light. “By combining these two techniques I think we’re going to be ready to answer standing questions related to heat transfer, we can make our way out of the rabbit hole,” Bucci says. The grant award from the U.S. DoE for Nuclear Energy Projects will aid in this and Bucci’s other research efforts.

      An idyllic Italian childhood

      Tackling difficult problems is not new territory for Bucci, who grew up in the small town of Città di Castello near Florence, Italy. Bucci’s mother was an elementary school teacher. His father used to have a machine shop, which helped develop Bucci’s scientific bent. “I liked LEGOs a lot when I was a kid. It was a passion,” he adds.

      Despite Italy going through a severe pullback from nuclear engineering during his formative years, the subject fascinated Bucci. Job opportunities in the field were uncertain but Bucci decided to dig in. “If I have to do something for the rest of my life, it might as well be something I like,” he jokes. Bucci attended the University of Pisa for undergraduate and graduate studies in nuclear engineering.

      His interest in heat transfer mechanisms took root during his doctoral studies, a research subject he pursued in Paris at the French Alternative Energies and Atomic Energy Commission (CEA). It was there that a colleague suggested work on the boiling water crisis. This time Bucci set his sights on NSE at MIT and reached out to Professor Jacopo Buongiorno to inquire about research at the institution. Bucci had to fundraise at CEA to conduct research at MIT. He arrived just a couple of days before the Boston Marathon bombing in 2013 with a round-trip ticket. But Bucci has stayed ever since, moving on to become a research scientist and then associate professor at NSE.

      Bucci admits he struggled to adapt to the environment when he first arrived at MIT, but work and friendships with colleagues — he counts NSE’s Guanyu Su and Reza Azizian as among his best friends — helped conquer early worries.

      The integration of artificial intelligence

      In addition to diagnostics for boiling, Bucci and his team are working on ways of integrating artificial intelligence and experimental research. He is convinced that “the integration of advanced diagnostics, machine learning, and advanced modeling tools will blossom in a decade.”

      Bucci’s team is developing an autonomous laboratory for boiling heat transfer experiments. Running on machine learning, the setup decides which experiments to run based on a learning objective the team assigns. “We formulate a question and the machine will answer by optimizing the kinds of experiments that are necessary to answer those questions,” Bucci says, “I honestly think this is the next frontier for boiling,” he adds.

      “It’s when you climb a tree and you reach the top, that you realize that the horizon is much more vast and also more beautiful,” Bucci says of his zeal to pursue more research in the field.

      Even as he seeks new heights, Bucci has not forgotten his origins. Commemorating Italy’s hosting of the World Cup in 1990, a series of posters showcasing a soccer field fitted into the Roman Colosseum occupies pride of place in his home and office. Created by Alberto Burri, the posters are of sentimental value: The (now deceased) Italian artist also hailed from Bucci’s hometown — Città di Castello. More

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      in Energy

      A better way to quantify radiation damage in materials

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      It was just a piece of junk sitting in the back of a lab at the MIT Nuclear Reactor facility, ready to be disposed of. But it became the key to demonstrating a more comprehensive way of detecting atomic-level structural damage in materials — an approach that will aid the development of new materials, and could potentially support the ongoing operation of carbon-emission-free nuclear power plants, which would help alleviate global climate change.

      A tiny titanium nut that had been removed from inside the reactor was just the kind of material needed to prove that this new technique, developed at MIT and at other institutions, provides a way to probe defects created inside materials, including those that have been exposed to radiation, with five times greater sensitivity than existing methods.

      The new approach revealed that much of the damage that takes place inside reactors is at the atomic scale, and as a result is difficult to detect using existing methods. The technique provides a way to directly measure this damage through the way it changes with temperature. And it could be used to measure samples from the currently operating fleet of nuclear reactors, potentially enabling the continued safe operation of plants far beyond their presently licensed lifetimes.

      The findings are reported today in the journal Science Advances in a paper by MIT research specialist and recent graduate Charles Hirst PhD ’22; MIT professors Michael Short, Scott Kemp, and Ju Li; and five others at the University of Helsinki, the Idaho National Laboratory, and the University of California at Irvine.

      Rather than directly observing the physical structure of a material in question, the new approach looks at the amount of energy stored within that structure. Any disruption to the orderly structure of atoms within the material, such as that caused by radiation exposure or by mechanical stresses, actually imparts excess energy to the material. By observing and quantifying that energy difference, it’s possible to calculate the total amount of damage within the material — even if that damage is in the form of atomic-scale defects that are too small to be imaged with microscopes or other detection methods.

      The principle behind this method had been worked out in detail through calculations and simulations. But it was the actual tests on that one titanium nut from the MIT nuclear reactor that provided the proof — and thus opened the door to a new way of measuring damage in materials.

      The method they used is called differential scanning calorimetry. As Hirst explains, this is similar in principle to the calorimetry experiments many students carry out in high school chemistry classes, where they measure how much energy it takes to raise the temperature of a gram of water by one degree. The system the researchers used was “fundamentally the exact same thing, measuring energetic changes. … I like to call it just a fancy furnace with a thermocouple inside.”

      The scanning part has to do with gradually raising the temperature a bit at a time and seeing how the sample responds, and the differential part refers to the fact that two identical chambers are measured at once, one empty, and one containing the sample being studied. The difference between the two reveals details of the energy of the sample, Hirst explains.

      “We raise the temperature from room temperature up to 600 degrees Celsius, at a constant rate of 50 degrees per minute,” he says. Compared to the empty vessel, “your material will naturally lag behind because you need energy to heat your material. But if there are changes in the energy inside the material, that will change the temperature. In our case, there was an energy release when the defects recombine, and then it will get a little bit of a head start on the furnace … and that’s how we are measuring the energy in our sample.”

      Hirst, who carried out the work over a five-year span as his doctoral thesis project, found that contrary to what had been believed, the irradiated material showed that there were two different mechanisms involved in the relaxation of defects in titanium at the studied temperatures, revealed by two separate peaks in calorimetry. “Instead of one process occurring, we clearly saw two, and each of them corresponds to a different reaction that’s happening in the material,” he says.

      They also found that textbook explanations of how radiation damage behaves with temperature weren’t accurate, because previous tests had mostly been carried out at extremely low temperatures and then extrapolated to the higher temperatures of real-life reactor operations. “People weren’t necessarily aware that they were extrapolating, even though they were, completely,” Hirst says.

      “The fact is that our common-knowledge basis for how radiation damage evolves is based on extremely low-temperature electron radiation,” adds Short. “It just became the accepted model, and that’s what’s taught in all the books. It took us a while to realize that our general understanding was based on a very specific condition, designed to elucidate science, but generally not applicable to conditions in which we actually want to use these materials.”

      Now, the new method can be applied “to materials plucked from existing reactors, to learn more about how they are degrading with operation,” Hirst says.

      “The single biggest thing the world can do in order to get cheap, carbon-free power is to keep current reactors on the grid. They’re already paid for, they’re working,” Short adds.  But to make that possible, “the only way we can keep them on the grid is to have more certainty that they will continue to work well.” And that’s where this new way of assessing damage comes into play.

      While most nuclear power plants have been licensed for 40 to 60 years of operation, “we’re now talking about running those same assets out to 100 years, and that depends almost fully on the materials being able to withstand the most severe accidents,” Short says. Using this new method, “we can inspect them and take them out before something unexpected happens.”

      In practice, plant operators could remove a tiny sample of material from critical areas of the reactor, and analyze it to get a more complete picture of the condition of the overall reactor. Keeping existing reactors running is “the single biggest thing we can do to keep the share of carbon-free power high,” Short stresses. “This is one way we think we can do that.”

      Sergei Dudarev, a fellow at the United Kingdom Atomic Energy Authority who was not associated with this work, says this “is likely going to be impactful, as it confirms, in a nice systematic manner, supported both by experiment and simulations, the unexpectedly significant part played by the small invisible defects in microstructural evolution of materials exposed to irradiation.”

      The process is not just limited to the study of metals, nor is it limited to damage caused by radiation, the researchers say. In principle, the method could be used to measure other kinds of defects in materials, such as those caused by stresses or shockwaves, and it could be applied to materials such as ceramics or semiconductors as well.

      In fact, Short says, metals are the most difficult materials to measure with this method, and early on other researchers kept asking why this team was focused on damage to metals. That was partly because reactor components tend to be made of metal, and also because “It’s the hardest, so, if we crack this problem, we have a tool to crack them all!”

      Measuring defects in other kinds of materials can be up to 10,000 times easier than in metals, he says. “If we can do this with metals, we can make this extremely, ubiquitously applicable.” And all of it enabled by a small piece of junk that was sitting at the back of a lab.

      The research team included Fredric Granberg and Kai Nordlund at the University of Helsinki in Finland; Boopathy Kombaiah and Scott Middlemas at Idaho National Laboratory; and Penghui Cao at the University of California at Irvine. The work was supported by the U.S. National Science Foundation, an Idaho National Laboratory research grant, and a Euratom Research and Training program grant. More

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      in Energy

      Fusion’s newest ambassador

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      When high school senior Tuba Balta emailed MIT Plasma Science and Fusion Center (PSFC) Director Dennis Whyte in February, she was not certain she would get a response. As part of her final semester at BASIS Charter School, in Washington, she had been searching unsuccessfully for someone to sponsor an internship in fusion energy, a topic that had recently begun to fascinate her because “it’s not figured out yet.” Time was running out if she was to include the internship as part of her senior project.

      “I never say ‘no’ to a student,” says Whyte, who felt she could provide a youthful perspective on communicating the science of fusion to the general public.

      Posters explaining the basics of fusion science were being considered for the walls of a PSFC lounge area, a space used to welcome visitors who might not know much about the center’s focus: What is fusion? What is plasma? What is magnetic confinement fusion? What is a tokamak?

      Why couldn’t Balta be tasked with coming up with text for these posters, written specifically to be understandable, even intriguing, to her peers?

      Meeting the team

      Although most of the internship would be virtual, Balta visited MIT to meet Whyte and others who would guide her progress. A tour of the center showed her the past and future of the PSFC, one lab area revealing on her left the remains of the decades-long Alcator C-Mod tokamak and on her right the testing area for new superconducting magnets crucial to SPARC, designed in collaboration with MIT spinoff Commonwealth Fusion Systems.

      With Whyte, graduate student Rachel Bielajew, and Outreach Coordinator Paul Rivenberg guiding her content and style, Balta focused on one of eight posters each week. Her school also required her to keep a weekly blog of her progress, detailing what she was learning in the process of creating the posters.

      Finding her voice

      Balta admits that she was not looking forward to this part of the school assignment. But she decided to have fun with it, adopting an enthusiastic and conversational tone, as if she were sitting with friends around a lunch table. Each week, she was able to work out what she was composing for her posters and her final project by trying it out on her friends in the blog.

      Her posts won praise from her schoolmates for their clarity, as when in Week 3 she explained the concept of turbulence as it relates to fusion research, sending her readers to their kitchen faucets to experiment with the pressure and velocity of running tap water.

      The voice she found through her blog served her well during her final presentation about fusion at a school expo for classmates, parents, and the general public.

      “Most people are intimidated by the topic, which they shouldn’t be,” says Balta. “And it just made me happy to help other people understand it.”

      Her favorite part of the internship? “Getting to talk to people whose papers I was reading and ask them questions. Because when it comes to fusion, you can’t just look it up on Google.”

      Awaiting her first year at the University of Chicago, Balta reflects on the team spirit she experienced in communicating with researchers at the PSFC.

      “I think that was one of my big takeaways,” she says, “that you have to work together. And you should, because you’re always going to be missing some piece of information; but there’s always going to be somebody else who has that piece, and we can all help each other out.” More

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      in Energy

      Pursuing progress at the nanoscale

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      Last fall, a team of five senior undergraduate nuclear engineering students met once a week for dinners where they took turns cooking and debated how to tackle a particularly daunting challenge set forth in their program’s capstone course, 22.033 (Nuclear Systems Design Project).

      In past semesters, students had free reign to identify any real-world problem that interested them to solve through team-driven prototyping and design. This past fall worked a little differently. The team continued the trend of tackling daunting problems, but instead got an assignment to explore a particular design challenge on MIT’s campus. Rising to the challenge, the team spent the semester seeking a feasible way to introduce a highly coveted technology at MIT.

      Housed inside a big blue dome is the MIT Nuclear Reactor Laboratory (NRL). The reactor is used to conduct a wide range of science experiments, but in recent years, there have been multiple attempts to implement an instrument at the reactor that could probe the structure of materials, molecules, and devices. With this technology, researchers could model the structure of a wide range of materials and complex liquids made of polymers or containing nanoscale inhomogeneities that differ from the larger mass. On campus, researchers for the first time could conduct experiments to better understand the properties and functions of anything placed in front of a neutron beam emanating from the reactor core.

      The impact of this would be immense. If the reactor could be adapted to conduct this advanced technique, known as small-angle neutron scattering (SANS), it would open up a whole new world of research at MIT.

      “It’s essentially using the nuclear reactor as an incredibly high-performance camera that researchers from all over MIT would be very interested in using, including nuclear science and engineering, chemical engineering, biological engineering, and materials science, who currently use this tool at other institutions,” says Zachary Hartwig, Nuclear Systems Design Project professor and the MIT Robert N. Noyce Career Development Professor.

      SANS instruments have been installed at fewer than 20 facilities worldwide, and MIT researchers have previously considered implementing the capability at the reactor to help MIT expand community-wide access to SANS. Last fall, this mission went from long-time campus dream to potential reality as it became the design challenge that Hartwig’s students confronted. Despite having no experience with SANS, the team embraced the challenge, taking the first steps to figure out how to bring this technology to campus.

      “I really loved the idea that what we were doing could have a very real impact,” says Zoe Fisher, Nuclear Systems Design Project team member and now graduate nuclear engineering student.

      Each fall, Hartwig uses the course to introduce students to real-world challenges with strict constraints on solutions, and last fall’s project came with plenty of thorny design questions for students to tackle. First was the size limitation posed by the space available at MIT’s reactor. In SANS facilities around the world, the average length of the instrument is 30 meters, but at NRL, the space available is approximately 7.5 meters. Second, these instruments can cost up to $30 million, which is far outside NRL’s proposed budget of $3 million. That meant not only did students need to design an instrument that would work in a smaller space, but also one that could be built for a tenth of the typical cost.

      “The challenge was not just implementing one of these instruments,” Hartwig says. “It was whether the students could significantly innovate beyond the ‘traditional’ approach to doing SANS to meet the daunting constraints that we have at the MIT Reactor.”

      Because NRL actually wants to pursue this project, the students had to get creative, and their creative potential was precisely why the idea arose to get them involved, says Jacopo Buongiorno, the director of science and technology at NRL and Tokyo Electric Power Company Professor in Nuclear Engineering. “Involvement in real-world projects that answer questions about feasibility and cost of new technology and capabilities is a key element of a successful undergraduate education at MIT,” Buongiorno says.

      Students say it would have been impossible to tackle the problem without the help of co-instructor Boris Khaykovich, a research scientist at NRL who specializes in neutron instrumentation.

      Over the past two decades, Khaykovich has watched as SANS became the most popular technique for analyzing material structure. As the amount of available SANS beam time at the few facilities that exist became more competitive, access declined. Today only the experiments passing the most stringent review get access. What Khaykovich hopes to bring to MIT is improved access to SANS by designing an instrument that will be suitable for a majority of run-of-the-mill experiments, even if it’s not as powerful as state-of-the-art national SANS facilities. Such an instrument can still serve a wider range of researchers who currently have few opportunities to pursue SANS experiments.

      “In the U.S., we don’t have a simple, small, day-to-day SANS instrument,” Khaykovich says.

      With Khaykovich’s help, nuclear engineering undergraduate student Liam Hines says his team was able to go much further with their assessment than they would’ve starting from scratch, with no background in SANS. This project was unlike anything they’d ever been asked of as MIT students, and for students like Hines, who contributed to NRL research his entire time on campus, it was a project that hit close to home. “We were imagining this thing that might be designed at MIT,” Hines says.

      Fisher and Hines were joined by undergraduate nuclear engineering student team members Francisco Arellano, Jovier Jimenez, and Brendan Vaughan. Together, they devised a design that surprised both Khaykovich and Hartwig, identifying creative solutions that overcame all limitations and significantly reduced cost.

      Their team’s final project featured an adaptation of a conical design that was recently experimentally tested in Japan, but not generally used. The conical design allowed them to maximize precision while working within the other constraints, resulting in an instrument design that exceeded Hartwig’s expectations. The students also showed the feasibility of using an alternative type of glass-based low-cost neutron detector to calibrate the scattering data. By avoiding the need for a traditional detector based on helium-3, which is increasingly scarce and exorbitantly expensive, such a detector would dramatically reduce cost and increase availability. Their final presentation indicated the day-to-day SANS instrument could be built at only 4.5 meters long and with an estimated cost less than $1 million.

      Khaykovich credited the students for their enthusiasm, bouncing ideas off each other and exploring as much terrain as possible by interviewing experts who implemented SANS at other facilities. “They showed quite a perseverance and an ability to go deep into a very unfamiliar territory for them,” Khaykovich says.

      Hines says that Hartwig emphasized the importance of fielding expert opinions to more quickly discover optimal solutions. Fisher says that based on their research, if their design is funded, it would make SANS “more accessible to research for the sake of knowledge,” rather than dominated by industry research.

      Hartwig and Khaykovich agreed the students’ final project results showed a baseline of how MIT could pursue SANS technology cheaply, and when NRL proceeds with its own design process, Hartwig says, “The student’s work might actually change the cost of the feasibility of this at MIT in a way that if we hadn’t run the class, we would never have thought about doing.”

      Buongiorno says as they move forward with the project, NRL staff will consult students’ findings.

      “Indeed, the students developed original technical approaches, which are now being further explored by the NRL staff and may ultimately lead to the deployment of this new important capability on the MIT campus,” Buongiorno says.

      Hartwig says it’s a goal of the Nuclear Systems Design Project course to empower students to learn how to lead teams and embrace challenges, so they can be effective leaders advancing novel solutions in research and industry. “I think it helps teach people to be agile, to be flexible, to have confidence that they can actually go off and learn what they don’t know and solve problems they may think are bigger than themselves,” he says.

      It’s common for past classes of Nuclear Systems Design Project students to continue working on ideas beyond the course, and some students have even launched companies from their project research. What’s less common is for Hartwig’s students to actively serve as engineers pointed to a particular campus problem that’s expected to be resolved in the next few years.

      “In this case, they’re actually working on something real,” Hartwig says. “Their ideas are going to very much influence what we hope will be a facility that gets built at the reactor.”

      For students, it was exciting to inform a major instrument proposal that will soon be submitted to federal funding agencies, and for Hines, it became a chance to make his mark at NRL.

      “This is a lab I’ve been contributing to my entire time at MIT, and then through this project, I finished my time at MIT contributing in a much larger sense,” Hines says. More

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      in Energy

      Evan Leppink: Seeking a way to better stabilize the fusion environment

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      “Fusion energy was always one of those kind-of sci-fi technologies that you read about,” says nuclear science and engineering PhD candidate Evan Leppink. He’s recalling the time before fusion became a part of his daily hands-on experience at MIT’s Plasma Science and Fusion Center, where he is studying a unique way to drive current in a tokamak plasma using radiofrequency (RF) waves. 

      Now, an award from the U.S. Department of Energy’s (DOE) Office of Science Graduate Student Research (SCGSR) Program will support his work with a 12-month residency at the DIII-D National Fusion Facility in San Diego, California.

      Like all tokamaks, DIII-D generates hot plasma inside a doughnut-shaped vacuum chamber wrapped with magnets. Because plasma will follow magnetic field lines, tokamaks are able to contain the turbulent plasma fuel as it gets hotter and denser, keeping it away from the edges of the chamber where it could damage the wall materials. A key part of the tokamak concept is that part of the magnetic field is created by electrical currents in the plasma itself, which helps to confine and stabilize the configuration. Researchers often launch high-power RF waves into tokamaks to drive that current.

      Leppink will be contributing to research, led by his MIT advisor Steve Wukitch, that pursues launching RF waves in DIII-D using a unique compact antenna placed on the tokamak center column. Typically, antennas are placed inside the tokamak on the outer edge of the doughnut, farthest from the central hole (or column), primarily because access and installation are easier there. This is known as the “low-field side,” because the magnetic field is lower there than at the central column, the “high-field side.” This MIT-led experiment, for the first time, will mount an antenna on the high-field side. There is some theoretical evidence that placing the wave launcher there could improve power penetration and current drive efficiency. And because the plasma environment is less harsh on this side, the antenna will survive longer, a factor important for any future power-producing tokamak.

      Leppink’s work on DIII-D focuses specifically on measuring the density of plasmas generated in the tokamak, for which he developed a “reflectometer.” This small antenna launches microwaves into the plasma, which reflect back to the antenna to be measured. The time that it takes for these microwaves to traverse the plasma provides information about the plasma density, allowing researchers to build up detailed density profiles, data critical for injecting RF power into the plasma.

      “Research shows that when we try to inject these waves into the plasma to drive the current, they can lose power as they travel through the edge region of the tokamak, and can even have problems entering the core of the plasma, where we would most like to direct them,” says Leppink. “My diagnostic will measure that edge region on the high-field side near the launcher in great detail, which provides us a way to directly verify calculations or compare actual results with simulation results.”

      Although focused on his own research, Leppink has excelled at priming other students for success in their studies and research. In 2021 he received the NSE Outstanding Teaching Assistant and Mentorship Award.

      “The highlights of TA’ing for me were the times when I could watch students go from struggling with a difficult topic to fully understanding it, often with just a nudge in the right direction and then allowing them to follow their own intuition the rest of the way,” he says.

      The right direction for Leppink points toward San Diego and RF current drive experiments on DIII-D. He is grateful for the support from the SCGSR, a program created to prepare graduate students like him for science, technology, engineering, or mathematics careers important to the DOE Office of Science mission. It provides graduate thesis research opportunities through extended residency at DOE national laboratories. He has already made several trips to DIII-D, in part to install his reflectometer, and has been impressed with the size of the operation.

      “It takes a little while to kind of compartmentalize everything and say, ‘OK, well, here’s my part of the machine. This is what I’m doing.’ It can definitely be overwhelming at times. But I’m blessed to be able to work on what has been the workhorse tokamak of the United States for the past few decades.” More

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      in Energy

      MIT expands research collaboration with Commonwealth Fusion Systems to build net energy fusion machine, SPARC

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      MIT’s Plasma Science and Fusion Center (PSFC) will substantially expand its fusion energy research and education activities under a new five-year agreement with Institute spinout Commonwealth Fusion Systems (CFS).

      “This expanded relationship puts MIT and PSFC in a prime position to be an even stronger academic leader that can help deliver the research and education needs of the burgeoning fusion energy industry, in part by utilizing the world’s first burning plasma and net energy fusion machine, SPARC,” says PSFC director Dennis Whyte. “CFS will build SPARC and develop a commercial fusion product, while MIT PSFC will focus on its core mission of cutting-edge research and education.”

      Commercial fusion energy has the potential to play a significant role in combating climate change, and there is a concurrent increase in interest from the energy sector, governments, and foundations. The new agreement, administered by the MIT Energy Initiative (MITEI), where CFS is a startup member, will help PSFC expand its fusion technology efforts with a wider variety of sponsors. The collaboration enables rapid execution at scale and technology transfer into the commercial sector as soon as possible.

      This new agreement doubles CFS’ financial commitment to PSFC, enabling greater recruitment and support of students, staff, and faculty. “We’ll significantly increase the number of graduate students and postdocs, and just as important they will be working on a more diverse set of fusion science and technology topics,” notes Whyte. It extends the collaboration between PSFC and CFS that resulted in numerous advances toward fusion power plants, including last fall’s demonstration of a high-temperature superconducting (HTS) fusion electromagnet with record-setting field strength of 20 tesla.

      The combined magnetic fusion efforts at PSFC will surpass those in place during the operations of the pioneering Alcator C-Mod tokamak device that operated from 1993 to 2016. This increase in activity reflects a moment when multiple fusion energy technologies are seeing rapidly accelerating development worldwide, and the emergence of a new fusion energy industry that would require thousands of trained people.

      MITEI director Robert Armstrong adds, “Our goal from the beginning was to create a membership model that would allow startups who have specific research challenges to leverage the MITEI ecosystem, including MIT faculty, students, and other MITEI members. The team at the PSFC and MITEI have worked seamlessly to support CFS, and we are excited for this next phase of the relationship.”

      PSFC is supporting CFS’ efforts toward realizing the SPARC fusion platform, which facilitates rapid development and refinement of elements (including HTS magnets) needed to build ARC, a compact, modular, high-field fusion power plant that would set the stage for commercial fusion energy production. The concepts originated in Whyte’s nuclear science and engineering class 22.63 (Principles of Fusion Engineering) and have been carried forward by students and PSFC staff, many of whom helped found CFS; the new activity will expand research into advanced technologies for the envisioned pilot plant.

      “This has been an incredibly effective collaboration that has resulted in a major breakthrough for commercial fusion with the successful demonstration of revolutionary fusion magnet technology that will enable the world’s first commercially relevant net energy fusion device, SPARC, currently under construction,” says Bob Mumgaard SM ’15, PhD ’15, CEO of Commonwealth Fusion Systems. “We look forward to this next phase in the collaboration with MIT as we tackle the critical research challenges ahead for the next steps toward fusion power plant development.”

      In the push for commercial fusion energy, the next five years are critical, requiring intensive work on materials longevity, heat transfer, fuel recycling, maintenance, and other crucial aspects of power plant development. It will need innovation from almost every engineering discipline. “Having great teams working now, it will cut the time needed to move from SPARC to ARC, and really unleash the creativity. And the thing MIT does so well is cut across disciplines,” says Whyte.

      “To address the climate crisis, the world needs to deploy existing clean energy solutions as widely and as quickly as possible, while at the same time developing new technologies — and our goal is that those new technologies will include fusion power,” says Maria T. Zuber, MIT’s vice president for research. “To make new climate solutions a reality, we need focused, sustained collaborations like the one between MIT and Commonwealth Fusion Systems. Delivering fusion power onto the grid is a monumental challenge, and the combined capabilities of these two organizations are what the challenge demands.”

      On a strategic level, climate change and the imperative need for widely implementable carbon-free energy have helped orient the PSFC team toward scalability. “Building one or 10 fusion plants doesn’t make a difference — we have to build thousands,” says Whyte. “The design decisions we make will impact the ability to do that down the road. The real enemy here is time, and we want to remove as many impediments as possible and commit to funding a new generation of scientific leaders. Those are critically important in a field with as much interdisciplinary integration as fusion.” More