image: Schematic of fast ions (black spirals) interacting with plasma waves (color) in a fusion experiment. The theoretical methods used to study fast ions in plasmas have also been used to describe the dynamics governing the evolution of galaxies.
Credit: Photo courtesy of Steve Allen, a physicist at the DOE's Lawrence Livermore National Laboratory, and adapted by Mike Van Zeeland, a physicist at General Atomics
More than 120 staff and 80 students and interns from the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) attended the American Physical Society’s Division of Plasma Physics (APS-DPP) Conference from Oct 30 to Nov. 3 in Denver. This annual meeting brings together the division’s 2,500 members whose collective research into plasma, the electrically charged fourth state of matter, touches fusion, astrophysics, manufacturing and medicine, among other applications.
More than 10 researchers connected to PPPL presented invited talks, papers, and posters.
A handful of PPPL research papers were also highlighted in the conference’s selective virtual press room. Authors included Vinícius Duarte, staff research physicist; Lan Gao, research physicist; Shaun Haskey, staff research physicist; Jeff Lestz, Princeton University alumnus and current General Atomics staff physicist; and Hantao Ji, PPPL physicist and Princeton University professor of astrophysics. Staff research physicist Sophia Malko took over the Lab’s Instagram account with live video footage from the event.
Full versions of the press releases are accessible here.
Award-winning research
Several PPPL scientists received awards for their research at the APS-DPP conference. Felix Parra Diaz, head of PPPL’s Theory Department, became a 2023 Fellow of the American Physical Society, and Princeton University postdoctoral research fellow in astrophysical sciences Ian Ochs received the Marshall N. Rosenbluth Outstanding Doctoral Thesis Award. PPPL principal research physicist Hong Qin received the 2023 John Dawson Award for Excellence in Plasma Physics Research, along with Philip Morrison of the University of Texas at Austin and Eric Sonnendrücker of the Max Planck Institute for Plasma Physics in Germany, for establishing and shaping the field of geometric algorithms that preserve fundamental structures in plasma physics calculations.
More than 135 students presented posters, 30 of whom were undergraduates hosted by PPPL through the U.S. Department of Energy’s Science Undergraduate Laboratory Internship (SULI) program and several other programs at PPPL last summer. John Labbatte, a student at the University of Maryland and one of PPPL’s SULI students, was among five undergraduates to receive awards for best posters. Labbatte won for his poster titled, “Analyzing Mode Stability to Identify Stable Operating Regions for the Novel SMall Aspect Ratio Tokamak (SMART).” Meg Fairborn of Whitworth University, another former PPPL intern, won for research she conducted at the University of Wisconsin. Her poster was titled, “GPU-Accelerated Grid-Free Monte Carlo Methods for Evaluating Heat Transport in Stellarators.”
Science education and plasma demonstrations
Arturo Dominguez, head of PPPL’s Science Education Department and a member of the executive committee that organized the conference, led a panel discussion on the Pathways to Fusion Collaborative Center, which PPPL leads. In addition, Deedee Ortiz, science education program manager, and Shannon Swilley Greco, senior program leader, gave talks at the conference. The science education staff also teamed with PPPL volunteers to give plasma demonstrations to students at the Plasma Science Student Expo and participated in the Plasma Science Teacher Day.
“This conference was really successful and showed that there’s a lot of momentum in public engagement, artificial intelligence and public-private partnerships,” Dominguez said. “Also, while there was a virtual component, it was great to see more folks participate in person.”
Below are summaries of the research releases highlighted in the press room.
Scientists explore how drag affects heating of fusion plasma
Researchers: Vinícius Duarte and Jeff Lestz
Just as there are waves in the ocean, waves can also occur in an electrically charged gas called plasma, which is composed of free electrons and ions. One of the major problems facing fusion power is determining how to make the plasma hot enough to sustain a fusion reaction without generating waves that might damage the fusion device.
To heat the plasma to the extreme temperatures necessary to produce fusion power requires an initial population of hot, or sometimes called “fast,” ions. However, these fast ions can resonate with waves in the plasma, similar to pushing someone on a swing, giving the waves energy and causing them to grow. If the waves grow too large, they can kick those same fast ions out of the plasma, cooling it off and reducing the fusion power that can be generated. These findings showed how drag between particles can affect whether plasma reaches temperatures necessary for fusion.
New experiments detect processes driving solar flares, magnetic storms
Researchers: Lan Gao, Hantao Ji
Solar flares and related geomagnetic storms can disrupt cell phone services, damage satellites, endanger astronauts, and affect the power grid and pipelines. PPPL physicists have for the first time experimentally detected two mechanisms that can help explain the astrophysical phenomena that cause solar flares.
The breakthrough experiment focused on magnetic reconnection, the separation and reconnection of the magnetic fields in plasma. Magnetic reconnection occurs throughout the universe and can cause explosive bursts of plasma during solar flares and auroras in Earth’s atmosphere.
Researchers have long proposed a link between reconnection and two plasma phenomena: the generation of energetic particles and acoustic or sound waves. But few had been directly observed. Now, the first direct experimental evidence for such links was observed in an experimental platform dubbed the Micro-MRX, a much smaller version of the Magnetic Reconnection Experiment (MRX) at PPPL.
New insights into fueling next-generation fusion power plants
Researcher: Shaun Haskey
Bringing fusion to the grid will require a thorough understanding of how to properly fuel next-generation fusion power plants. In magnetically confined fusion devices such as tokamaks, strong magnetic fields contain plasma (a collection of ions and electrons) under the high pressure and temperature needed for the fusion reaction to occur. One method to keep the plasma hot and deliver more fuel inside a tokamak is to inject a beam of high-energy neutral particles that transfer their energy to the plasma particles through collisions.
Predicting the distribution of neutral particle densities and velocities inside a tokamak is challenging due to uncertainties related to the way they make their way into the plasma to provide fueling. New measurements of high-energy neutral particles by PPPL researchers provide more clarity. The measurements were made in the DIII-D National Fusion Facility using spectroscopy — a diagnostic technique that studies how light and matter interact. DIII-D is a tokamak operated by General Atomics for the U.S. Department of Energy.
“High-energy neutrals provide a significant fraction of fueling in present-day tokamaks, so it’s important we understand their speed and location,” Haskey said. “It’s likely these high-energy neutrals can provide improved pathways to fuel in the conditions expected at fusion-reactor scales.”
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PPPL, on Princeton University's Forrestal Campus in Plainsboro, New Jersey, is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for creating fusion energy. The university manages the Laboratory for the U.S. Department of Energy’s Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science