TTF Roundup: NEEP presenters and graduate student wins Best Student Poster

The University of Wisconsin- Madison hosted the 2024 US-EU Transport Task Force (TTF) Workshop, chaired by Dr. George McKee (NEEP) in Asheville, North Carolina. 80 researchers from the US, Germany, UK, Italy, Norway, and China gathered to present, discuss, and debate the latest research in the field of turbulence and transport physics, including experiments, theory, and simulation results and their performance impacts for magnetically confined fusion plasmas.

NEEP graduate student Samuel Stewart received the Best Student Poster Award for his poster “Characterization of Turbulence in Negative Triangularity DIII-D Plasmas using Beam Emission Spectroscopy.” Stewart is a PhD student working with Professor Benedikt Geiger and Dr. George McKee in the Plasma Turbulence and Spectroscopy Group.

To produce energy from fusion reactions, similar to what happens in the sun, gasses need to be heated up to millions of degrees to produce a plasma. These plasmas must be confined in magnetic “containers,” called flux surfaces. However, heat from the plasma can escape the container through fast, chaotic vibrations called turbulence. Stewart’s research focuses on how the shape of the container affects the turbulence and how well the plasma can be confined. The shape Stewart focuses on is a negative triangularity in donut-shaped devices called tokamaks, where the outer edge of the donut is flattened. Using a fast, camera-like detector, Stewart was able to show turbulence is reduced in the negative triangularity shape. Future fusion devices could use this shape to garner better plasma confinement and device performance.

“Plasma turbulence is an exciting field as it is still very exploratory,” Stewart says. In plasma theory, there are many unanswered questions. As an experimentalist, Stewart can come across counterintuitive results that have yet to be well described by theory. “Plasma shaping is also an exciting topic as it provides a pathway to optimize reactor designs as well as come up with new reactor concepts.”

UW-Madison has a rich history of fusion research, which continues to flourish through a vibrant research community. In addition to Stewart’s poster, the following posters and oral presentations were given by graduate students, staff scientists, and faculty members from UW-Madison:

• Xijie Qin, Graduate Student, Plenary Presentation, “Measurement of Turbulence-driven Reynolds Stress and Its Contribution to Toroidal Intrinsic Rotation in the DIII-D Tokamak”
• Benjamin Faber, Scientist, Plenary Presentation, “Understanding and Optimizing 3D Turbulence in HSX”
• Kevin Gill, Graduate Student, Oral Presentation, “Convolutional Neural Networks for Real-Time Classification of Plasma Confinement Regimes via High-Bandwidth Edge Fluctuation Data in DIII-D”
• Elizabeth Perez, Graduate Student, Oral Presentation, “Gyrokinetic simulations of pedestal turbulence during NBI-only and NBI+ECRH plasmas”
• Maximillian Major, Graduate Student, Oral Presentation, “Microtearing Mode Characterization with Charge eXchange Imaging on the DIII-D* Tokamak”
• Joseph Duff, Graduate Student, Poster, “Stellarator Turbulence Optimization Based on Flux Surface Triangularity”
• Augustus Azelis, Graduate Student, Poster, “Transport Statistics near the Linear Threshold of Toroidal Ion Temperature Gradient Driven”
• Benedikt Geiger, Professor, Poster, “Experimental investigation of heat- and impurity transport based on highspeed charge exchange recombination spectroscopy at W7-X”
• Filipp Khabanov, Postdoctoral Research Associate, Poster, “Properties of edge turbulence near the density limit in negative triangularity plasmas at DIII-D”
• Zheng Yan, Scientist, Poster, “Turbulence and Flow Dynamics Approaching the Density Limit in L-mode Plasmas at DIII-D”
• George McKee, Scientist, Poster, “Turbulence and Transport dependence on ρ* in Low-Rotation H-Mode Plasmas on DIII-D”

Featured image: NEEP graduate student Samuel Stewart (right) presents his poster at the 2024 TTF Workshop. Photo credit: Dr. George McKee