Word count: 1954
April 21, 2021
The next five years would crush Ryan Chaban’s idealism and cripple Richard Reksoatmodjo’s confidence.
Chaban sat perched on his chair in a San Diego coffee shop, anxiously waiting for someone. He'd never met this person before, but he would spend the next five to seven years working alongside them. They would be his sole partner in the Fusion Science and Plasma Physics research lab at William & Mary.
By pure coincidence, the two researchers found themselves in the same city on the same day. What else to do but meet up for coffee?
Chaban does not remember his initial impression of Reksoatmodjo but acknowledges that “Richard was less tattooed and pierced” back in 2017. Reksoatmodjo, on the other hand, remembers exactly what he thought upon seeing Chaban for the first time: “He looked just like a physicist!”
These two young researchers were about to embark on a long, arduous journey to earn their PhDs in nuclear fusion science. But for now, all they had in mind was a cup of coffee and a chat about fusion energy.
Fusion is the act of smashing small atoms (usually variants of Hydrogen) together to release energy. Fusion energy is attractive for a plethora of reasons: 1) There is no risk of nuclear meltdown; the worst that can happen is the atoms don’t combine to release energy, 2) The reaction itself produces no carbon dioxide or long-lived nuclear waste, and 3) Fusion can unlock enough energy from a single glass of seawater to power the average U.S. home for two months.
All this potential exists, yes. But the trick is releasing it, and fusion technology is far from perfect. If fusion is to become truly feasible -enough so that you might pay affordable rates for emission-free energy - it will be thanks to the stalwart research efforts of those like Reksoatmodjo and Chaban.
If fusion were a recipe, the ingredient list would be two items long. Unlike a half caf, vanilla bean frappuccino with extra whip and chocolate, it’d be more like an americano. But instead of espresso beans and water, the two ingredients1 needed to produce fusion are Deuterium and Tritium. Deuterium consists of one positive proton and one neutral neutron. Tritium is barely any more complex, with one proton and two neutrons per atom.
How to find these ingredients? Sea water brims with Deuterium, and scientists “breed” Tritium precisely for fusion experiments. These are the ingredients. Brewing is the tricky part. For atoms to fuse, they must move almost 2,000 miles a second. At that speed, you could go from New York to London and back in just 3.5 seconds! To speed atoms up, researchers energize them by raising the atoms’ temperatures to five times hotter than the sun. And to ensure atoms are close enough to smash together, pressures mount to 150 billion times that of the earth’s atmosphere.
The conditions are extreme, but the concept is simple. Smash an atom of Tritium into an atom of Deuterium with enough oomph, and voila, out comes Helium (two protons + two neutrons), one neutron, and energy. Two protons and three neutrons go in. Two protons and three neutrons come out... and energy too, in the form of heat. Heat like that boils water into steam, which turns turbines, which generates electricity and powers an espresso machine.
Chaban hails fusion as “the futuristic solution to climate change,” and has been itching to turn this dream of safe abundant energy into a reality. The concept of clean energy also galvanized Reksoatmodjo. But unlike Chaban, Reksoatmodjo had eyes for all sorts of applied physics. Specifically, Reksoatmodjo knew he wanted to do something with plasma.
Plasma is a “superheated” gas, which means it is a gas heated to a temperature above its boiling point. In gas, electrons are bound tight to their atoms. But if you heat that gas up -- like researchers do inside a fusion reactor -- the electrons gain energy. Get up to 12,000 degrees Fahrenheit, and there’s so much energy buzzing in these electrons that they can lose their grip on the atomic nucleus. The negatively charged electron whizes off and leaves a positively charged atom in its wake.
In essence, plasma is a scalding soup made of positive charges and negative charges. This means electricity and magnets can influence the behavior of plasma by attracting and repelling the charged particles. Nuclear fusion scientists exploit this fact in fusion reactors. Using ten thousand tonnes of magnets, they subtly mold the plasma into the form of a ring. In this ring, atoms crash and fuse, while the researchers harvest energy from the collisions.
These concepts - fusion, plasma, Deuterium - were small talk for Chaban and Reksoatmodjo. Big talk waited around the corner. The following fall, the two entered graduate school. Without a beat, their faculty advisor sat them down and gave them a roadmap of the next five years.
Year 1: Classes
Year 2: More classes
Year 3: Figuring things out
Year 4: Peer-reviewed journal article
Year 5: Two more articles, plus a dissertation
And that was that. Reksoatmodjo and Chaban were let loose.
Chaban and Reksoatmodjo’s faculty advisor directed them to investigate one nuclear reactor each. She assigned Chaban to MAST (Mega Ampere Spherical Tokamak) in the United Kingdom and Reksoatmodjo to Alcator C-Mod, a retired reactor from the Massachusetts Institute of Technology. Fusion reactors like MAST and C-Mod are “stepping stones” to the “gold standard of net energy,” explains Reksoatmodjo. By net energy, he means an energy profit. Only when fusion generates more energy than it consumes will commercial fusion reactors enter the realm of possibility.
Fusion scientists have yet to reach this holy grail of net energy. For one thing, heating the plasma to around 275 million degrees Celsius demands one lightning bolt worth ofenergy every 10-20 seconds. What’s more, that energy escapes whenever the stunningly hot plasma gets too close to the relatively cold vessel walls. Preventing this energy loss completely would require a “perfect magnetic bottle” says Reksoatmodjo, “which is a pipe dream." So he and other scientists work to minimize energy loss and reach a point of good enough.
Keeping things hot isn’t the only challenge. Scientists and engineers must move fuel in and take impurities out of the reaction chamber, too. "How do you put more gas into something that's the temperature of the sun?" asks Chaban. This was exactly the research question he and Reksoatmodjo needed to answer.
As the sole graduate students in Dr. Saskia Mordijck’s Fusion Science and Plasma Physics group, Chaban and Reksoatmodjo had only each other for support - a far cry from their past summer internships filled with mentors and peers eager to lend a hand.
Their mission: to study what happens at plasma’s edges in a fusion reaction chamber. This edge region, called the Scrape Off Layer (SOL), behaves drastically differently than plasma in the center of the reactor. If scientists cannot accurately predict and control plasma in the Scrape Off Layer, the 275 million degree Celsius plasma might jettison into the vessel walls, causing energy levels to plummet and damage the million-dollar machinery.
Understanding this border behavior baffles scientists, Reksoatmodjo and Chaban included. “The more papers I read, the more I realized I didn’t know shit,” admits Reksoatmodjo. William & Mary coursework barely broached complex plasma mannerisms, and the two graduate students scrambled to overcome their own bafflement.
The endgame of Chaban’s work with British reactor MAST was to describe turbulence in the outermost plasma flows. MAST held the answers to his query, but gigabytes and gigabytes of data buried the gold nuggets of relevant information. The reality of the project was well beyond what Chaban expected.. The project morphed and shrunk. Then it shrunk again. Chaban held the dregs of an original idea, but nothing publishable. "You can do a lot of work, but if you don’t [get published], it counts as zero," he notes.
Chaban had lost his way in the dark and murky waters of research. Meanwhile, Reksaoatmodjo had no inkling whether his own research trajectory led to a welcoming harbor or toward a buffeting storm.
Reksoatmodjo stood waist deep in complex computer coding. Using experimental data, he set up simulations of the plasma and the plasma environment. Although a single second of real-time plasma action requires eight hours of processing, the simulations enable scientists to make predictions and look deeper into why plasma behaves a certain way inside the fusion vessel.
Reksoatmodjo refined these simulations for the better part of two years. Although the work progressed, Reksoatmodjo himself felt increasingly lost. He was unsure of his own goals, and other goals were imposed by faculty. He wishes he’d foreseen the constant self-questioning of his capabilities and course of action. Several times he considered throwing in the towel and dropping out. “My first two and a half years absolutely sucked,” Reksoatmodjo unloads.
Reksoatmodjo didn’t quit. Instead, he clung on by his fingertips. He saw a therapist to help him persevere through the frustrations and doubts and, piece by piece, assembled a valuable research contribution. In 2020, the journal Nuclear Materials and Energy accepted Reksoatmodjo’s first paper for publication. Seeing the news brought “absolute elation.” He recounts: “I think I air fisted and teared up a little bit even. It felt like the previous three years of labor had finally paid off.”
Chaban still struggled. Although he strained to push forward his work with MAST, nothing came of it. Two and a half years of work spiraled down the drain. “Where your failures delay your life for one to two years. That’s brutal,” Chaban grieves.
It was time – past time, really – for Plan B. Chaban turned his attention back to the California reactor DIII-D, where he had spent a summer during undergrad. In operation since the late 1980s by General Atomics, DIII-D derives its name from the plasma’s “D” shape. Chaban’s now needed to understand how different fuels affect fusion performance by analyzing the experimental data. "The data is all there,” he points out. “It's up to me to sift through that data... interpret what the data means."
Chaban and Reksoatmodjo have one more year of their trek remaining. If all goes well, Reksoatmodjo plans to defend his dissertation in April 2022, but Chaban’s road to a thesis defense may take one to two years longer.
When asked what comes after, Reksoatmodjo says the next step will be to continue on as a postdoc. His larger aim, however, is to teach physics at a small college. Chaban doesn’t know what the future holds, but he posits Dominion Energy might be his next destination.
Although the past four years shattered their rose-colored glasses, both researchers still affirm fusion’s vitality for a decarbonized energy landscape. Chaban exhorts fusion’s potential for on-demand power, while Reksoatmodjo asserts seawater-based fuels would require less transportation, mining, and earth extraction work than fossil fuel-based energy.
If this carbon-free method of power generation is to become a reality, it will be thanks to the tenacity of those like Reksoatmodjo and Chaban. “The research we do is just a drop in the ocean," Reksoatmodjo points out. Researchers around the world unite in pursuit of fusion - to deliver safe, clean, and abundant energy.
To stay in the loop on the latest fusion developments, check out phys.org. Or to learn about the world’s biggest fusion reactor, look at iter.org.
Today, Chaban and Reksoatmodjo are much different people than the expectant and somewhat naïve pair who met for coffee in San Diego’s early summertime. Throughout five years of trials and tribulations, they learned hard truths while withstanding the rigors of graduate school.
Fusion, it turns out, transforms more than atoms; it transforms its practitioners.