Sheaths at the edge of plasma, including afterglows

Professor John Goree

Abstract: Sheaths are the non-neutral boundary regions between a plasma and a solid surface. They occur widely, for all kinds of plasmas that are exposed to surfaces, including those of a spacecraft, the regolith of the Moon or other planetary bodies, electrodes in a low-temperature laboratory plasma, and the first wall of a fusion plasma.
I will review the basics of sheaths, in general, including power-law descriptions of the electric potential inside a sheath. Then, I will present results for a laboratory glow-discharge plasma. A particle-in-cell PIC code, with Monte-Carlo collisions with neutral atoms is used to simulate a capacitively coupled radio-frequency plasma. Results will include the sheath potential profile during a steadily powered plasma, and as it develops during the afterglow when the RF power is switched off.
The simulations were performed by Peter Hartmann and Zoltán Donkó of the Wigner Research Center in Budapest Hungary. The simulations are based on experiments performed in my laboratory with Neeraj Chaubey and Anton Kananovich.
Work was supported at Iowa by DOE No. DE-SC0025444 and NSF No. PHY-2510501