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Tag: plasma physics

  • Ever Wondered What Nuclear Fusion Looks Like? We Have Pics

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    Nuclear fusion may always be ten years away, but the technological breakthroughs aiming to get us there are already here—including an imaging technique that vividly shows why fusion is said to harness the energy of the stars.

    A recent release from UK-based startup Tokamak Energy presents an unprecedentedly colorful image of a fusion reaction, captured using a high-speed color camera at 16,000 frames per second. The mesmerizing footage is a treat for the eyes, but the different colors each represent valuable information for fusion researchers investigating the efficacy of the reactor.

    For example, the bright pink glow represents the edge of the hydrogen plasma. The green streaks come from lithium ions that trace the path of the plasma around the tokamak, a donut-shaped instrument that confines hot plasma for fusion reactions. The plasma’s core is “too hot to emit visible light,” the company explained, but the other color signals offer invaluable information on how different fusion ingredients interact with one another.

    Decoding the colors of fusion

    Simply, nuclear fusion combines two lightweight atoms—most often deuterium and tritium, two hydrogen isotopes—to generate massive amounts of energy. Unlike fission, which splits heavy atoms, fusion doesn’t leave behind harmful, radioactive waste.

    Fusion would be the ideal alternative to fossil fuels—if we can get it to scale commercially, that is. Although the field has made significant strides over the years, the general understanding is that practical fusion energy is still years away.

    Again, fusion’s goal is to replicate stellar energy on Earth, which means fusion experiments involve many extreme conditions that are notoriously difficult to investigate. As with any technology, researchers want to understand how and where things can go wrong—especially when dealing with volatile material like the super-hot plasma confined inside a reactor.

    Inching toward better performance

    Naturally, physicists have been hard at work finding a workaround. The new footage was part of an investigation into X-point radiator regimes, an approach that seeks to gain better control of plasma flow to “reduce wear without compromising performance,” according to Tokamak Energy.

    “The color camera is especially helpful for experiments like these,” said Laura Zhang, a plasma physicist with Tokamak Energy, in the release. “It helps us immediately identify whether the gaseous impurities we’re introducing are radiating at the expected place and whether lithium powders are penetrating to the plasma core.”

    “This work is advancing our understanding of plasma behavior as we scale up to energy-producing fusion devices,” added the researchers. “The addition of color imaging is already providing valuable insights into how materials interact within the plasma.”

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    Gayoung Lee

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  • Scientists Just Took a Giant Step Toward Scaling Up Nuclear Fusion

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    A team of researchers at MIT think they may have lowered one of the major barriers to achieving large-scale nuclear fusion—taking us one step closer to making an abundant form of energy a reality.

    By harnessing the same processes that power stars, we would have access to a clean, safe, and practically limitless energy source. Scientists have built reactors to try and tame fusion, with one of the most explored being the tokamak. Essentially a donut-shaped tube that uses strong magnets to confine the plasma needed to power fusion reactions, the tokamak has shown great potential. But to fully realize that, scientists must first navigate the potential pitfalls that such energy carries with it, including how to slow down a fusion reaction once it is in progress.

    That’s where the new research comes in: Using a combination of physics and machine learning, the researchers predicted how the plasma inside a tokamak reactor would behave given a set of initial conditions—something that researchers have long puzzled over (it is hard to look inside a fusion reactor mid-run, after all). The paper was published Monday in Nature Communications.

    “For fusion to be a useful energy source, it’s going to have to be reliable,” Allen Wang, study lead author and a graduate student at MIT, told MIT News. “To be reliable, we need to get good at managing our plasmas.”

    With great power comes great risks

    When a tokamak reactor is fully running, the plasma current inside can circulate at speeds of up to about 62 miles (100 kilometers) per second and at temperatures of 180 million degrees Fahrenheit (100 million degrees Celsius). That is hotter than the Sun’s core.

    If the reactor has to be shut down for any reason, operators initiate a process to “ramp down” the plasma current, slowly de-energizing it. But this process is tricky, and the plasma can cause “scrapes and scarring to the tokamak’s interior—minor damage that still requires considerable time and resources to repair,” the researchers explained.

    “Uncontrolled plasma terminations, even during rampdown, can generate intense heat fluxes damaging the internal walls,” explained Wang. “Quite often, especially with the high-performance plasmas, rampdowns actually can push the plasma closer to some instability limits. So, it’s a delicate balance.

    Indeed, any misstep in operating fusion reactors can be costly. In an ideal world, researchers would be able to run tests in working tokamaks, but because fusion is still not efficient, running one of these reactors is incredibly costly, and most facilities will only run them a few times a year.

    Looking to the wisdom of physics

    For their model, the team found a delightfully clever method to overcome the limitations in data collection—they simply went back to the fundamental rules of physics. They paired their model’s neural network with another model describing plasma dynamics, and then trained the model on data from the TCV, a small experimental fusion device in Switzerland. The dataset included information about variations in the plasma’s starting temperature and energy levels, as well as during, and at the end of each experimental run.

    From there, the team used an algorithm to generate “trajectories” that laid out for the reactor operators how the plasma would likely behave as the reaction progressed. When they applied the algorithm to actual TCV runs, they found that following the model’s “trajectory” instructions were perfectly able to guide operators to ramp the device safely down.

    “We did it a number of times,” Wang said. “And we did things much better across the board. So, we had statistical confidence that we made things better.”

    “We’re trying to tackle the science questions to make fusion routinely useful,” he added. “What we’ve done here is the start of what is still a long journey. But I think we’ve made some nice progress.”

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    Gayoung Lee

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  • Princeton University awards plasma physics graduate student Suying Jin a highly selective honorific fellowship

    Princeton University awards plasma physics graduate student Suying Jin a highly selective honorific fellowship

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    Jin expressed deep appreciation on receiving the fellowship. “I feel truly honored, and I’m fortunate to be at an institution that lifts up its students in this way,” she said. “I am also deeply grateful for all the support, academic and otherwise, that has made this possible.”

    The Program in Plasma Physics is based at the Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) and is a graduate program within the Department of Astrophysical Sciences at Princeton University. Graduates of the program have shaped the field of plasma physics in recent decades, working in academia, national laboratories, industry and beyond.

    Spontaneously arising order

    Jin’s dissertation is investigating the challenging question of how plasmas self-organize in the presence of magnetic fields. “You see it happening all the time, everywhere in the universe, where you have order spontaneously arising from turbulence or chaos,” she said. “I like to go after things that defy intuition and much about the mechanism by which this self-organization occurs remains mysterious.  

    When her advisor, principal research physicist Ilya Dodin, offered Jin several thesis topics to choose from, “Suying fearlessly chose the most challenging project over low-hanging fruits,” Dodin said. “She felt that although immediate rewards were not to be expected, the results of that project would be more important in the long run. I have much respect for that attitude,” he said. “Suying is an outstanding researcher and a classic role model who strongly deserves a Princeton honorific fellowship.”

    Jin traces her passionate interest in plasma science to her preparation for a final exam at the University of California, Los Angeles  (UCLA), where she graduated in physics with honors in 2018. “I was working my way through an electrodynamics textbook, and I came across this problem that introduced me to the whole idea of plasma,” she said. “It was my first time thinking about what would happen if you had a bunch of charged particles together and it seemed like anything would be possible in a medium like that.”

    Basic Science

    While her thesis topic “is basic science and not fusion focused, ultimately, I think the fusion effort will benefit greatly from just fundamental plasma research,” she said. “There’s a lot we still need to understand about plasmas, period.”

    Her dedication to learning extends to teaching, which she has pursued as a teaching assistant at the graduate and undergraduate levels. She’s taught in Dodin’s graduate class in plasma waves, where “she was very proactive and did a great job,” he recalls. She also helped teach an undergraduate course in fusion and fission that has expanded her interest in real-world problems.

    Her research has led to frequent peer-reviewed publications, including five papers as a first author and two as a co-author. In addition, she shares a patent disclosure with two PPPL physicists.

    Outside the classroom, Jin has been an active participant in plasma programs. She was a cofounder of Princeton Women in Plasma Physics (PWiPP), whose mission includes promoting “a supportive community for women and gender minorities in plasma physics at Princeton.”  She has lectured at plasma physics workshops and been a panelist and discussion leader at a local conference for undergraduate women in physics.

    Tae Kwon Do

    When not deeply engaged in plasma physics, Jin pursues long-time hobbies including the Korean martial art Tae Kwon Do, in which she holds a black belt and has practiced for 15 years. She also enjoys cooking and playing the piano.

    Looking ahead, Jin says she would prefer a teaching job to a purely research position and sees herself “continuing down the path of academia. “I’ve had such fantastic mentors from day one when I entered this field, and I would really like to work with students to pass that mentorship along.”

    The Program in Plasma Physics has graduated more than 300 students since it began in 1959.
    In an environment that, over the past few decades, has seen enormous changes in the fields of plasma physics and controlled fusion, the program has consistently focused on fundamentals in physics and mathematics and on intense exposure to contemporary experimental and theoretical research in plasma physics. Learn more.

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    Princeton Plasma Physics Laboratory

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