WVU physicists unlock plasma’s mysteries with lasers

West Virginia University researchers are developing new laser-based techniques to observe plasma behavior in unprecedented detail, opening a window into interactions that shape technologies ranging from computer chips and spacecraft engines to next-generation fusion energy systems.

Plasmas, electrically charged gases known as the fourth state of matter, are central to technologies ranging from microchip manufacturing to advanced spacecraft propulsion. Because plasmas consist of charged particles, they conduct electricity and react to electric and magnetic fields, making them useful across a range of industrial and scientific applications.

By observing plasma behavior in unprecedented detail, scientists including Thomas Steinberger, assistant professor, and Jacob McLaughlin, research assistant professor, both in the Department of Physics and Astronomy at the WVU Eberly College of Arts and Sciences, will examine how charged particles and energy move between plasmas and material surfaces.

When plasma meets a solid surface, a thin electrical boundary layer known as a plasma sheath develops, Steinberger explained. Within that sheath, positively charged particles are accelerated toward a material surface and transfer energy that can significantly influence surface behavior and lifetime.

Plasma sheaths play a critical role in how quickly materials wear down, how efficiently devices operate and how long plasma-facing components last.

To improve scientists' abilities to predict and influence the behavior of plasma sheaths, a $633,833 National Science Foundation award supports Steinberger's development of new laser-based methods for studying how plasma sheaths form when surfaces emit large numbers of electrons.

"This is one of those regions in plasma physics that we know is incredibly important, but it's also extremely difficult to measure without affecting the system you're trying to study," Steinberger said. "What we're building allows us to observe these boundary regions in a way that hasn't really been possible before."

The research tests longstanding plasma theories related to the formation of inverted sheaths that behave differently from the classical sheath.

Under certain conditions, Steinberger said, researchers predict that plasma sheaths can transition into inverted sheaths. In an inverted sheath, the flow of positively charged particles called ions toward the material surface is dramatically reduced or even reversed - a stark difference from their behavior in a classical plasma sheath. This fundamentally changes how the plasma interacts with the material.

Despite extensive theoretical work, those phenomena have rarely been observed directly, because many traditional plasma diagnostics disturb the environments they are attempting to measure.

But Steinberger will measure both the motion of ions and the behavior of electrical fields near material surfaces without disrupting the plasma itself. To do so, he'll employ two techniques - laser-induced fluorescence, which uses lasers to excite atoms, and quantum beat spectroscopy, which measures differences in electron energy levels that reveal electric field strengths.

By combining the techniques, he hopes to produce the first co-registered, two-dimensional optical maps of ion motion, electric fields and potential structures from the plasma core to a surface boundary.

"We can look at how ions are moving while also measuring the electric fields at the same time," McLaughlin said. "That gives us a much higher level of confidence in what's actually happening near the surface."

McLaughlin and Steinberger's long-term goal is to understand whether it's possible to actively control ion flow to a surface.

"If we can control how many ions actually hit a surface, if we can reduce or manipulate that ion flux, there are a lot of applications where that becomes extremely valuable, with huge implications for technologies where plasma damage is a major concern," Steinberger said.

In semiconductor manufacturing, for example, controlling ion bombardment could improve the precision of plasma-processing tools used to etch microchips and electronic components.

Similar plasma-boundary processes are important in spacecraft propulsion systems and fusion-energy devices, where reducing damaging ion bombardment could improve efficiency and extend the lifespan of plasma-facing materials.

Over the next three years, Steinberger and his team will build and commission new diagnostic systems, calibrate them in controlled plasma experiments, then use them to investigate whether inverted plasma sheaths form under ordinary low-temperature plasma conditions.

After mapping how ions move and how electric fields change, they'll be able to determine whether those interactions can be put to use in plasma-based technologies.

The NSF grant also supports doctoral student and undergraduate training opportunities at WVU, including development of a new advanced undergraduate plasma physics laboratory module and outreach efforts focused on students from rural and underserved communities across West Virginia.

By giving students hands-on experience with advanced plasma diagnostics and cutting-edge research, Steinberger and McLaughlin hope to prepare the next generation of scientists to tackle some of the most challenging questions in plasma science while expanding opportunities to pursue STEM careers for students across West Virginia.

"We've been very fortunate with the students we've had involved," Steinberger said. "They come in motivated, asking the right questions and bringing the kind of intuition that makes this work exciting."

-WVU-

ks/6/23/26

MEDIA CONTACT: Rachel Brosky
Media Manager
WVU Strategic Communications and Marketing
304-293-3990, [email protected]

Call 1-855-WVU-NEWS for the latest West Virginia University news and information from WVUToday.