skip to main content

DOE PAGESDOE PAGES

This content will become publicly available on March 19, 2019

Title: Floating potential of emitting surfaces in plasmas with respect to the space potential

The potential difference between a floating emitting surface and the plasma surrounding it has been described by several sheath models, including the space-charge-limited sheath, the electron sheath with high emission current, and the inverse sheath produced by charge-exchange ion trapping. Our measurements reveal that each of these models has its own regime of validity. We determine the potential of an emissive filament relative to the plasma potential, emphasizing variations in emitted current density and neutral particle density. The potential of a filament in a diffuse plasma is first shown to vanish, consistent with the electron sheath model and increasing electron emission. In a denser plasma with ample neutral pressure, the floating filament potential is positive, as predicted by a derived ion trapping condition. In conclusion, the filament floated negatively in a third plasma, where flowing ions and electrons and nonnegligible electric fields may have disrupted ion trapping. Depending on the regime chosen, emitting surfaces can float positively or negatively with respect to the plasma potential.
Authors:
 [1] ; ORCiD logo [2]
  1. Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Grant/Contract Number:
AC02-09CH11466
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 3; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1430533
Alternate Identifier(s):
OSTI ID: 1426846

Kraus, B. F., and Raitses, Y.. Floating potential of emitting surfaces in plasmas with respect to the space potential. United States: N. p., Web. doi:10.1063/1.5018335.
Kraus, B. F., & Raitses, Y.. Floating potential of emitting surfaces in plasmas with respect to the space potential. United States. doi:10.1063/1.5018335.
Kraus, B. F., and Raitses, Y.. 2018. "Floating potential of emitting surfaces in plasmas with respect to the space potential". United States. doi:10.1063/1.5018335.
@article{osti_1430533,
title = {Floating potential of emitting surfaces in plasmas with respect to the space potential},
author = {Kraus, B. F. and Raitses, Y.},
abstractNote = {The potential difference between a floating emitting surface and the plasma surrounding it has been described by several sheath models, including the space-charge-limited sheath, the electron sheath with high emission current, and the inverse sheath produced by charge-exchange ion trapping. Our measurements reveal that each of these models has its own regime of validity. We determine the potential of an emissive filament relative to the plasma potential, emphasizing variations in emitted current density and neutral particle density. The potential of a filament in a diffuse plasma is first shown to vanish, consistent with the electron sheath model and increasing electron emission. In a denser plasma with ample neutral pressure, the floating filament potential is positive, as predicted by a derived ion trapping condition. In conclusion, the filament floated negatively in a third plasma, where flowing ions and electrons and nonnegligible electric fields may have disrupted ion trapping. Depending on the regime chosen, emitting surfaces can float positively or negatively with respect to the plasma potential.},
doi = {10.1063/1.5018335},
journal = {Physics of Plasmas},
number = 3,
volume = 25,
place = {United States},
year = {2018},
month = {3}
}