Ion collection by planar Langmuir probes: Sheridan's model and its verification
Abstract
Data analysis from planar Langmuir probes normally assumes that the sheath effects are not significant in determining electron density and temperature when the Debye length is small compared to the probe radius. However, analysis of ion saturation current requires careful attention due to sheath expansion near the probe electrode. It is experimentally verified for the first time that Sheridan's numerical model [T. E. Sheridan, Phys. Plasmas 7, 3084 (2000)] provides a correct method to measure the ion saturation current for which the ion density agrees with the electron density in argon plasmas.
- Authors:
-
- Department of Engineering Physics, University of Wisconsin at Madison, Madison, Wisconsin 53706 (United States)
- Publication Date:
- OSTI Identifier:
- 20974899
- Resource Type:
- Journal Article
- Resource Relation:
- Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 3; Other Information: DOI: 10.1063/1.2715557; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ARGON; DATA ANALYSIS; DEBYE LENGTH; ELECTRODES; ELECTRON DENSITY; ELECTRON TEMPERATURE; ION DENSITY; ION TEMPERATURE; IONS; LANGMUIR PROBE; PLASMA; PLASMA DENSITY; PLASMA EXPANSION; PLASMA SHEATH; VERIFICATION
Citation Formats
Lee, Dongsoo, and Hershkowitz, Noah. Ion collection by planar Langmuir probes: Sheridan's model and its verification. United States: N. p., 2007.
Web. doi:10.1063/1.2715557.
Lee, Dongsoo, & Hershkowitz, Noah. Ion collection by planar Langmuir probes: Sheridan's model and its verification. United States. doi:10.1063/1.2715557.
Lee, Dongsoo, and Hershkowitz, Noah. Thu .
"Ion collection by planar Langmuir probes: Sheridan's model and its verification". United States.
doi:10.1063/1.2715557.
@article{osti_20974899,
title = {Ion collection by planar Langmuir probes: Sheridan's model and its verification},
author = {Lee, Dongsoo and Hershkowitz, Noah},
abstractNote = {Data analysis from planar Langmuir probes normally assumes that the sheath effects are not significant in determining electron density and temperature when the Debye length is small compared to the probe radius. However, analysis of ion saturation current requires careful attention due to sheath expansion near the probe electrode. It is experimentally verified for the first time that Sheridan's numerical model [T. E. Sheridan, Phys. Plasmas 7, 3084 (2000)] provides a correct method to measure the ion saturation current for which the ion density agrees with the electron density in argon plasmas.},
doi = {10.1063/1.2715557},
journal = {Physics of Plasmas},
number = 3,
volume = 14,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
DOI: 10.1063/1.2715557
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Particle-in-cell simulations of planar and cylindrical Langmuir probes: Floating potential and ion saturation current
Particle-in-cell and hybrid electron-Boltzmann simulations of planar and cylindrical Langmuir probes are compared with various probe theories. Floating potentials for planar and cylindrical probes are calculated and significant deviations from the typical approximation used for argon discharges of {approx}5T{sub e} are shown. The interpretation of simulated ion saturation currents by the orbital motion limited and the Laframboise theories result in an overestimation of the ion density. On the other hand, the cold-ion theory underestimates the ion density. These deviations are related to the overestimation and underestimation, respectively, of the ion orbital motion around cylindrical probes. The best agreement is obtainedmore »