A view inside of PHASMA, the primary experimental facility in the Center for KINETIC Plasma Physics at West Virginia University
MORGANTOWN, W.Va. — A paper co-authored by a West Virginia University physics alumnus has been recognized among the top early-career research publications in Physics of Plasmas.
Each year since 2022, the journal's editors and editorial board have selected outstanding papers authored by early-career researchers for inclusion in its Early Career Collection. To qualify, authors must be within five years of earning their doctoral degree, excluding career breaks such as family or medical leave, at the time of manuscript submission.
Among the researchers honored this year is Ripudaman Singh Nirwan, who earned his Ph.D. in physics from WVU in 2022. Nirwan collaborated with current and former members of the West Virginia University Department of Physics and Astronomy on a study examining how magnetic fields influence electron acceleration during magnetic reconnection, a fundamental plasma process linked to some of the most energetic events in the universe.
The paper, titled "Guide-field-dependent electron acceleration during electron-only magnetic reconnection in the PHAse Space MApping (PHASMA) experiment," builds on research that formed the foundation of Nirwan's doctoral dissertation. His thesis focused on reconnection-driven electron acceleration, the same phenomenon explored in the publication. Nirwan is now a postdoctoral researcher at the University of Washington, where he studies laser-induced fluorescence in Hall thrusters.
Magnetic reconnection occurs when magnetic field lines break apart and reconnect, releasing stored magnetic energy and converting it into plasma flows, heat, and high-energy particles. Scientists believe the process drives events ranging from solar fares to space-weather disturbances near Earth.
Using the PHASMA experiment, Nirwan and his collaborators investigated how the strength of a guide magnetic field affects electron acceleration during electron-only magnetic reconnection. By keeping the reconnecting magnetic field constant while varying the guide field strength, the researchers found that electron acceleration decreases significantly as the guide field becomes stronger.
Their results suggest that stronger guide fields create thicker current sheets, which weaken the parallel electric field responsible for accelerating electrons and ultimately reduce the efficiency of electron acceleration.
To capture the full range of electron behavior, the team combined two diagnostic techniques. Thomson scattering measured the thermal electron population and heating associated with reconnection, while a Retarding Field Energy Analyzer measured energetic, nonthermal electrons that Thomson scattering could not reliably detect.
The findings provide new experimental insight into particle acceleration in strongly magnetized plasmas and help bridge the gap between laboratory measurements and spacecraft observations of electron-only magnetic reconnection in astrophysical environments including Earth's magnetosheath.
Co-authors at West Virginia University include current graduate student Gustavo Elias Bartolo; postdoctoral researchers Dr. Sonu Yadav, Dr. Katey Stevenson, and Dr. Krishan Kumar; and Professor Earl Scime.
The paper is available to read in Physics of Plasmas.