Through the Donut's Hole

The quest for fusion energy in Columbia’s Plasma Lab.

By Sona Wink

In Everything, Everywhere All at Once (2022), a cosmic donut (more specifically, a bagel, but bear with me) possesses a gravitational pull so powerful that the protagonist must do everything in her power to steer clear of its magnetic tug. Unbeknownst to many, a cosmic donut of Columbia’s own sits in an unassuming nook in Mudd; much like Michelle Yeoh in Everything, I found myself inexplicably pulled toward its center.

Illustration by Jaqueline Subkhanberdina

Columbia’s Plasma Physics Laboratory houses the HBT-EP Tokamak, a machine that creates plasma in the shape of a donut. Lucia Rondini, CC ’23, worked at the Lab this past year and took me on a spontaneous Tokamak tour in the fall. As we wandered the Lab’s cavernous halls, Lucia explained how Columbia’s Tokamak is tiny compared to ITER, the world’s largest (yet still non-operational) fusion reactor and the result of a multinational megaproject. To my eyes, however, the HBT-EP looked massive (it takes up a space about the size of a Hamilton classroom) and dazzlingly complex: a patchwork of tubes, wires, see-through plastic, and metal panels weaving toward a rotund central organ. 

The closest I get to danger in my academic career is reading about wars that happened 100 years ago; in the Lab, students operate a machine that creates a lethally hot plasma. The space is peppered with signs reading “DANGER” that Lucia brushed past with total ease. Professor Michael Mauel, who has worked in plasma physics at Columbia since 1985, put the job of a Tokamak operator this way: “We’re taking a ring of hot gas at 100 million degrees, and we’re spinning it a couple centimeters from the walls, which are basically at room temperature.” 

Picture the Sun’s churning core: a place so hot and so pressurized (27,000,000 degrees Fahrenheit and 10 times denser than gold) that around 600 million tons of hydrogen nuclei collide and fuse each second, producing helium atoms. The resulting atom has less mass than the total of the initial two, and the excess mass becomes energy. We experience this fusion energy on Earth as sunlight. Tokamaks recreate the conditions inside the Sun to create fusion energy: Under extreme heat and pressure, hydrogen gas turns into plasma, wherein nuclear fusion takes place. Plasma is electrically charged, so Tokamaks confine it using magnetic coils. Fittingly, the name “Tokamak” is a Russian portmanteau for “toroidal chamber with magnetic coils” (“toroidal” means “donut-shaped”). 

Physicists have been working on the Tokamak for over 70 years in a quest to turn fusion energy into a viable source of power for society at large. Classified research into fusion began in the United States in the 1950s. Finding that fusion (unlike its more popular brother, fission) was too technically challenging to make bombs with, the U.S. and the Soviet Union mutually declassified their fusion research in 1958 at the Atoms for Peace conference. In the late 1970s, crises in the Middle East disrupted U.S. access to petroleum, precipitating an energy crisis and a wave of worry about the availability of fossil fuels. Fusion energy came into the national limelight along with other early forms of renewable energy as potential alternatives to fossil fuels. 

Much of the Lab’s infrastructure dates back to this initial burst of national interest in fusion. The space has, until recently, seen minimal renovation since its mid-century inception. The rooms, which feed into one another, are lined with metal cabinets painted a dusty gray-blue; the floors are plasticky and gray. Bits and pieces of machinery are scattered on every surface: a constellation of bits of metal, frayed coils of wire, tools, and doctoral dissertations. Whiteboards dot the walls, bearing physics equations scrawled in every color of Expo marker. 

As I walked through the Lab with Lucia, I noticed that while the vast majority of the space maintained its ’70s charm, there were some modern renovations. I chatted about the changes to the physical space of the Lab with Lucia and Rian Chandra, a sixth-year doctoral candidate in the Department of Applied Physics and Applied Mathematics who has worked at the Lab since 2017. Chandra described how the refurbishments, which include new carpets and a conference room, are physical manifestations of a renewed wave of interest in plasma physics. 

The climate crisis has precipitated a quest for renewable sources of energy, and fusion presents an attractive option: It has the potential to create significant amounts of energy without emitting carbon into the atmosphere, and it lacks the radioactive risks of fission. Today, the level of commercial and public excitement about fusion energy is comparable to that of the 1970s. In the spring of 2022, the White House held a summit titled “Developing a Bold Decadal Vision for Commercial Fusion Energy” where it rolled out several massive funding programs for fusion research led by the Department of Energy and encouraged private sector investment in fusion. In one such program, the DOE invested $46 million in eight private companies seeking to build fusion power plants. In winter 2022, scientists in a national laboratory in California accomplished a major milestone when they produced net energy gain for the first time in fusion’s history. (They used a process called inertial confinement, which involves shooting lasers into a small cylinder. Tokamaks use a different process called magnetic confinement.)   

As national interest in fusion has bloomed in the past three years, so has the Lab. Professor Carlos Paz-Soldan joined Applied Physics and Applied Mathematics in 2021 and has harnessed the national wave of interest to grow the Lab by acquiring grants, starting new projects, and expanding the Lab’s student population. Prior to 2021, Paz-Soldan estimated that there were few to no undergraduates working at the Lab; now, there are roughly 30. 

Lucia and Chandra explained how Paz-Soldan and his colleague Professor Elizabeth Paul, who joined the department in 2023, are younger than many of the other faculty in the department and have ushered in a “project-oriented mindset” to the Lab. Today’s burst of interest in fusion is characterized by a practical goal: bringing fusion to the grid, i.e., turning fusion into a reliable, cost-effective, self-sustaining form of energy that can be converted into electricity and used by society at large in place of fossil fuels. “You’d be hard-pressed to find someone here who doesn’t have climate change as their primary motivator,” Lucia told me. 

How long it will take to bring fusion to the grid is the subject of dispute. A 2023 report by the Fusion Energy Association made the optimistic claim that “25 companies think the first fusion plant will deliver electricity to the grid before 2035.” Paz-Soldan explained that he thinks “time and money are interchangeable” when it comes to developing fusion reactors, and that given enough investment in private development, the 2030s are a reasonable projection. 

The recent boom in private sector engagement in fusion is new, but academic interest in plasma physics is not. Mauel has worked in plasma physics at Columbia for nearly 40 years; while governmental and commercial interest in fusion energy has waxed and waned, academics like him have held steady. Chandra expressed admiration for Mauel, his advisor, who “came up in the field at a time when bringing fusion to the grid was not really something we were going to see in our lifetime.” Indeed, when I asked Mauel about his projection for when fusion would become a viable source of energy, he told me, “I just cannot begin to imagine that.”

Mauel’s keenness for the beauty of plasma was more than evident when I spoke with him. As he explained magnetic fields to me, he suddenly swiveled away to pull up a video. What to me looked like a gyrating purple blob tinged with orange was, in fact, a very important phenomenon in plasma physics: a disruption, which occurs when the plasma donut wiggles too much and touches the Tokamak’s walls. Mauel’s narration turned the otherwise abstract video into an action movie. “You might be able to see some glow, purple … It’s wiggling, it’s wiggling,” he whispered. Suddenly, the blob expanded with a flash. “WHOA! Isn’t that amazing?” 

Disruptions like the one in Mauel’s video pose a major challenge to physicists: They are one of the major barriers blocking fusion’s introduction to the grid. From a goal-oriented mindset, these disruptions are nuisances. To Mauel, they are delights. “If we can understand and prevent this sort of disruption phenomena,” he told me, “then fusion will be reliable and provide an electrical source. But you can probably tell from my reaction that what I’m most interested in is how cool that is!”