In the absence of electron emission, a floating plasma-facing dielectric charges negatively due to the higher mobility of electrons. A key question is: what energy is required to remove these surplus electrons from a charged surface? In this work, we present recent studies of laser-stimulated photodetachment (LSPD) of surface electrons following plasma exposure [1]. While photodetachment thresholds are commonly linked to electron affinity, our results show that the detachment yield depends strongly on the initial surface charge density and exhibits no clear correlation with tabulated electron affinity values under gas-discharge conditions. These findings provide new insight into surface charging and discharging dynamics, with implications for secondary electron emission and photoemission processes in plasma devices, including negative ion sources and dusty plasmas [2].
We also investigate plasma–wall interaction in the presence of electron emission, where multiple regimes arise, including classical, space-charge-limited, and inverse sheaths. Experiments demonstrate that emission strongly modifies sheath structure, electron energy balance, and wall heat flux [3]. Under strong emission, surfaces can float near or above the plasma potential, fundamentally altering plasma–surface coupling. These results highlight the need for kinetic descriptions and establish emitting boundaries as an effective tool to actively control plasma properties in low-pressure plasma systems, from emissive probe to plasma thrusters [4].
[1] Y. Ussenov, M. N. Shneider, S. Yatom, Y. Raitses, "Laser-stimulated photodetachment of electrons from the negatively charged dielectric substrates", Appl. Phys. Lett. 125, 254102 (2024)
[2] M. Schneider, Y. Raitses, S. Yatom, " Schottky effect on the wavelength threshold for the photo-detachment from charged metallic nanoparticles", J. Phys. D: Appl. Phys 56, 29LT01 (2023)
[3] B. F. Kraus and Y. Raitses, “Floating potential of emitting surfaces in plasmas with respect to the space potential”, Phys. Plasmas 25, 030701 (2018)
[4] Y. Raitses, I. D. Kaganovich, A. Khrabrov, D. Sydorenko, N. J. Fisch, A. Smolyakov, “Effect of Secondary Electron Emission on Electron Cross-Field Current in ExB Discharges”, IEEE Transactions on Plasma Science 39, 995 (2011)
This research was supported by the U.S. Department of Energy, Office of Fusion Energy Sciences, under Contract No. DE-AC02-09CH11466.
Bio:
Yevgeny Raitses is an expert in experimental plasma physics. He has an extensive publication record with more than 250 publications on physics of plasma-surface interactions, plasma thrusters, plasma-based synthesis and processing of nanomaterials, cross-field discharges, and plasma diagnostics. Raitses earned a doctoral degree in aerospace from Technion-Israel Institute of Technology in 1997. He was elected an Associate Fellow of the American Institute of Aeronautics and Astronauts in 2009 and a Fellow of the American Physical Society the following year. Among many honors, Raitses received PPPL’s Kaul Foundation Prize for Excellence in Plasma Physics Research and Technology Development in 2019. He is also a PPPL Distinguished Research Fellow since 2024.
Raitses is leading three main low temperature plasma projects at PPPL including the Princeton Collaborative Low Temperature Plasma Research Facility (http://pcrf.pppl.gov), the Plasma-enabled 2D Materials for Energy‑efficient Microelectronics project (PlasMat2D) which is a part of the Microelectronics Science Research Center “The Extreme Lithography & Materials via Co-Design” (ELMIC), https://sites.google.com/pppl.gov/elmic/ , and the Hall Thruster Experiment (HTX), htx.pppl.gov