Plasma edge in theory and experiment

Since 2025, Dr. Victoria Winters has been leading a new junior research group at the University of Greifswald to investigate the plasma edge at the IPP Stellarator Wendelstein 7-X – funded by the German Federal Ministry of Education and Research (BMFTR). Here she explains her research.

 

 

Which role does plasma boundary and exhaust physics in stellarators play for fusion research?

When people think of fusion, they often picture the burning plasma at the core. But the reality is, the boundary region plays a critical role in making fusion reactors viable for steady-state operation. Without a well-managed boundary, the whole system becomes unsustainable. Heat and particle exhaust are especially vital. If we don’t spread the heat effectively — for example, through radiation — we risk damaging or even melting the plasma-facing components. And if we fail to remove the helium “ash” produced by fusion, it leads to fuel dilution, which can choke off the self-sustaining reaction entirely. In stellarators, solving the exhaust challenge can be even more complex than in tokamaks. The geometry introduces different length scales and shifts the dominance of various transport phenomena. But that complexity comes with a silver lining: stellarators offer far more flexibility in shaping the magnetic geometry at the plasma boundary. That makes it a rich optimization problem — exciting for researchers — though it also means we’re still catching up in terms of understanding compared to the more mature tokamak designs. And with the rapid timelines envisioned by private fusion companies, we’re increasingly challenged to strike a balance between deep optimization and practical, near-term solutions.

What is the goal of your new junior research group?

Our group is focused on bridging the gap between present-day stellarator experiments and future reactor designs. To do this, we concentrate on validating advanced 3D simulation codes — a crucial step in making predictive modeling reliable for fusion applications. We take a hybrid approach, combining simulation and experiment. On the experimental side, we mature diagnostic techniques — such as Neon line ratio spectroscopy — and design validation experiments that test our models in reactor-relevant scenarios like detachment, i.e., the controlled cooling of the plasma at the divertor. On the simulation side, we continuously integrate new physical models and numerical techniques to improve fidelity and scope. We perform reactor-scale simulations to understand how performance changes as we extrapolate from present-day devices to future ones. Through this, we aim to uncover simple scaling relationships — with respect to device size, power, or geometry — that can be incorporated into stellarator systems codes to guide early-stage optimization.

What motivates you personally in your research?

I find the plasma boundary in stellarators to be an endlessly fascinating topic where I’m always learning something new. It’s a complex, multiscale system where atomic physics, plasma dynamics, and engineering all interact — and exploring it feels less like a job and more like a hobby I get to pursue professionally. Beyond that, I’m deeply motivated by the possibility of seeing the first fusion power plant in my lifetime. Fusion is a rare example of a truly multinational scientific community working toward a shared goal, and being part of that collaborative effort gives my work a sense of purpose.
 

Victoria Winters received her doctorate from the University of Wisconsin Madison in 2019. She then became a research assistant at the IPP. Dr. Winters' new junior research group at the Max Planck Institute for Plasma Physics (IPP) is funded by the German Federal Ministry of Research, Technology, and Space (BMFTR).