The shot that took just a few billionths of a second was 60 years in the making, and Alex Zylstra ’09 played a key role in its success. Just after 1 a.m. on Dec. 5, Zylstra and fellow scientists at the Lawrence Livermore National Laboratory’s National Ignition Facility (NIF) at last achieved fusion ignition. The energy produced by a controlled fusion reaction exceeded the amount required to fuel the process: 2.05 megajoules in, 3.15 megajoules out. For a tiny fraction of a second, they produced the brightest thing on earth.
Fusion, as the U.S. Department of Energy describes it, occurs when “two light nuclei combine to form a single heavier nucleus, releasing a large amount of energy.” The NIF scientists achieved a breakthrough that could someday lead to limitless clean energy to power the world, using the same reaction as the sun and stars.
News of the achievement came at a press conference at the Department of Energy in Washington, D.C. on Dec. 13. Zylstra joined a panel of experts to describe the successful experiment, which involved shooting 192 huge lasers at a target the size of a pea. The resulting temperature reached more than 100 million degrees. The pressure was more than double that at the center of the sun. The level of precision the experiment required was mind-boggling. “We had a debate over a laser setting equivalent to 5 trillionths of a meter,” Zylstra said at the press conference. “We had a discussion with the laser science team over timing discrepancies of 25 trillionths of a second.”
“When I saw the early data start coming in after 1 a.m on December 5th, I was incredibly excited,” Zylstra wrote in an email to Pomona, adding he had been “eager to work on validating the results before we went public.” Outside experts also provided peer review before the successful experiment was announced.
As principal experimentalist, Zylstra describes his role as twofold: “first, to be the primary scientist associated with executing a particular ‘shot,’ or experiment, and second, to guide a set of experiments to develop improvements or test hypotheses.” He describes the NIF as “a highly interdisciplinary endeavor,” so it is essential to work closely with the other teams—computational, design, measurement, laser and target fabrication, and operations.
Dwight Whitaker, chair of the Department of Physics and Astronomy at Pomona, was delighted but not surprised at Zylstra’s role in the groundbreaking experiment. Zylstra was in his junior year when Whitaker joined the Pomona College faculty and began setting up his lab. “I was trying to set up some difficult experiments and I was ecstatic when he joined the lab, because he was extraordinary,” Whitaker recalls. “Alex and I worked a lot of hours together. I used to turn knobs with him in the lab, and now he’s running one of the most complicated experiments ever created. That’s a pretty amazing feeling.”
Zylstra has focused on fusion ever since he started a doctoral program at the Massachusetts Institute of Technology after graduating from Pomona in 2009. As an undergraduate, he’d had the opportunity to see the NIF center being built and says that “it felt like a chance to work on something straight out of science fiction.”
Whitaker says that “fusion is so alluring. It’s like free energy” and could “solve one of the biggest problems facing humanity right now—the climate crisis.” But fusion research, like most other areas of science, is a long and arduous process. Physicists have been working on replicating the action of the sun for six decades. Whitaker thinks that “probably the personality trait you need to have as a physicist is the ability to grind through very unrewarding times, because experimental physics is usually a lesson in failure. Ninety percent of the things we do don’t work,” he says. “But each time you fail, you learn. I think that’s what fusion has been—lots of incremental steps and failures”—and then success.
Zylstra echoes that same sentiment in passing along advice for fellow Sagehens, especially students with a passion for science. "Some of the challenges in science or the world can seem daunting,” he says. “But with the right team, great things can happen. So pick what you’re interested in and go have an impact. For fusion specifically, the problem is not solved. We still have a lot of work to do and need help if it [is going to] have benefits for society.”