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Title: High accuracy plasma density measurement using hybrid Langmuir probe and microwave interferometer method

Abstract

High spatial resolution plasma density measurements have been taken as part of an investigation into magnetic nozzle physics at the NASA/MSFC Propulsion Research Center. These measurements utilized a Langmuir triple probe scanned across the measurement chord of either of two stationary rf interferometers. By normalizing the scanned profile to the microwave interferometer line-integrated density measurement for each electrostatic probe measurement, the effect of shot-to-shot variation of the line-integrated density can be removed. In addition, by summing the voltage readings at each radial position in a transverse scan, the line density can be reconstituted, allowing the absolute density to be determined, assuming that the shape of the profile is constant from shot to shot. The spatial and temporal resolutions of this measurement technique depend on the resolutions of the scanned electrostatic probe and the interferometer. The measurement accuracy is 9%-15%, which is on the order of the accuracy of the rf interferometer. The measurement technique was compared directly with both scanning rf interferometer and standard Langmuir probe theory. The hybrid technique compares favorably with the scanning rf interferometer, and appears more accurate than probe theory alone. Additionally, our measurement technique is generally applicable even for nonaxisymmetric plasmas.

Authors:
; ; ; ;  [1]
  1. Radiation Laboratory, University of Michigan, Ann Arbor, Michigan 48109 (United States)
Publication Date:
OSTI Identifier:
21024585
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 78; Journal Issue: 11; Other Information: DOI: 10.1063/1.2813885; (c) 2007 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:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ACCURACY; COMPARATIVE EVALUATIONS; DENSITY; ELECTRIC POTENTIAL; ELECTROSTATIC PROBES; INTERFEROMETERS; LANGMUIR PROBE; MICROWAVE RADIATION; NASA; NOZZLES; PLASMA; PLASMA DENSITY; PROPULSION; SHAPE; SPATIAL RESOLUTION

Citation Formats

Deline, C, Gilchrist, B E, Dobson, C, Jones, J E, Chavers, D G, and Propulsion Research Center, NASA/Marshall Space Flight Center, Huntsville, Alabama 35812. High accuracy plasma density measurement using hybrid Langmuir probe and microwave interferometer method. United States: N. p., 2007. Web. doi:10.1063/1.2813885.
Deline, C, Gilchrist, B E, Dobson, C, Jones, J E, Chavers, D G, & Propulsion Research Center, NASA/Marshall Space Flight Center, Huntsville, Alabama 35812. High accuracy plasma density measurement using hybrid Langmuir probe and microwave interferometer method. United States. https://doi.org/10.1063/1.2813885
Deline, C, Gilchrist, B E, Dobson, C, Jones, J E, Chavers, D G, and Propulsion Research Center, NASA/Marshall Space Flight Center, Huntsville, Alabama 35812. 2007. "High accuracy plasma density measurement using hybrid Langmuir probe and microwave interferometer method". United States. https://doi.org/10.1063/1.2813885.
@article{osti_21024585,
title = {High accuracy plasma density measurement using hybrid Langmuir probe and microwave interferometer method},
author = {Deline, C and Gilchrist, B E and Dobson, C and Jones, J E and Chavers, D G and Propulsion Research Center, NASA/Marshall Space Flight Center, Huntsville, Alabama 35812},
abstractNote = {High spatial resolution plasma density measurements have been taken as part of an investigation into magnetic nozzle physics at the NASA/MSFC Propulsion Research Center. These measurements utilized a Langmuir triple probe scanned across the measurement chord of either of two stationary rf interferometers. By normalizing the scanned profile to the microwave interferometer line-integrated density measurement for each electrostatic probe measurement, the effect of shot-to-shot variation of the line-integrated density can be removed. In addition, by summing the voltage readings at each radial position in a transverse scan, the line density can be reconstituted, allowing the absolute density to be determined, assuming that the shape of the profile is constant from shot to shot. The spatial and temporal resolutions of this measurement technique depend on the resolutions of the scanned electrostatic probe and the interferometer. The measurement accuracy is 9%-15%, which is on the order of the accuracy of the rf interferometer. The measurement technique was compared directly with both scanning rf interferometer and standard Langmuir probe theory. The hybrid technique compares favorably with the scanning rf interferometer, and appears more accurate than probe theory alone. Additionally, our measurement technique is generally applicable even for nonaxisymmetric plasmas.},
doi = {10.1063/1.2813885},
url = {https://www.osti.gov/biblio/21024585}, journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 11,
volume = 78,
place = {United States},
year = {Thu Nov 15 00:00:00 EST 2007},
month = {Thu Nov 15 00:00:00 EST 2007}
}