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Title: Effect of filament supports on emissive probe measurements

Abstract

We have constructed an emissive probe with a thin tungsten filament spot-welded across two nickel wires insulated with ceramic paint. We show that the ceramic supports covering the nickel wires have a large effect on the potential measurements in low-density plasmas. It is found that the potential measured by the emissive probe is more negative than the potential derived from a Langmuir probe current-voltage (I-V) characteristic curve when the plasma density is so low that the emitting filament remains immersed in the sheaths of the ceramic supports. The length of the filament L needs to be larger than about 2 Debye lengths (L > 2{lambda}{sub De}) in order to avoid the influence of the ceramic supports and to achieve reliable plasma potential measurements using emissive probes.

Authors:
;  [1];  [1];  [2]
  1. Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80309 (United States)
  2. NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309 (United States)
Publication Date:
OSTI Identifier:
22105357
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 84; Journal Issue: 1; Other Information: (c) 2013 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CERAMICS; DEBYE LENGTH; FILAMENTS; LANGMUIR PROBE; NICKEL; PLASMA DENSITY; PLASMA POTENTIAL; PLASMA SHEATH; TUNGSTEN

Citation Formats

Wang, X., Howes, C. T., NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309, Horanyi, M., NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309, Department of Physics, University of Colorado, Boulder, Colorado 80309, Robertson, S., and Department of Physics, University of Colorado, Boulder, Colorado 80309. Effect of filament supports on emissive probe measurements. United States: N. p., 2013. Web. doi:10.1063/1.4776201.
Wang, X., Howes, C. T., NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309, Horanyi, M., NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309, Department of Physics, University of Colorado, Boulder, Colorado 80309, Robertson, S., & Department of Physics, University of Colorado, Boulder, Colorado 80309. Effect of filament supports on emissive probe measurements. United States. https://doi.org/10.1063/1.4776201
Wang, X., Howes, C. T., NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309, Horanyi, M., NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309, Department of Physics, University of Colorado, Boulder, Colorado 80309, Robertson, S., and Department of Physics, University of Colorado, Boulder, Colorado 80309. 2013. "Effect of filament supports on emissive probe measurements". United States. https://doi.org/10.1063/1.4776201.
@article{osti_22105357,
title = {Effect of filament supports on emissive probe measurements},
author = {Wang, X. and Howes, C. T. and NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309 and Horanyi, M. and NASA Lunar Science Institute: Colorado Center for Lunar Dust and Atmospheric Studies, Boulder, Colorado 80309 and Department of Physics, University of Colorado, Boulder, Colorado 80309 and Robertson, S. and Department of Physics, University of Colorado, Boulder, Colorado 80309},
abstractNote = {We have constructed an emissive probe with a thin tungsten filament spot-welded across two nickel wires insulated with ceramic paint. We show that the ceramic supports covering the nickel wires have a large effect on the potential measurements in low-density plasmas. It is found that the potential measured by the emissive probe is more negative than the potential derived from a Langmuir probe current-voltage (I-V) characteristic curve when the plasma density is so low that the emitting filament remains immersed in the sheaths of the ceramic supports. The length of the filament L needs to be larger than about 2 Debye lengths (L > 2{lambda}{sub De}) in order to avoid the influence of the ceramic supports and to achieve reliable plasma potential measurements using emissive probes.},
doi = {10.1063/1.4776201},
url = {https://www.osti.gov/biblio/22105357}, journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 1,
volume = 84,
place = {United States},
year = {Tue Jan 15 00:00:00 EST 2013},
month = {Tue Jan 15 00:00:00 EST 2013}
}