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Title: A resistively heated CeB{sub 6} emissive probe

Abstract

The plasma potential, V{sub p}, is a key quantity in experimental plasma physics. Its spatial gradients directly yield the electrostatic field present. Emissive probes operating under space-charge limited emission conditions float close to V{sub p} even under time-varying conditions. Throughout their long history in plasma physics, they have mostly been constructed with resistively heated tungsten wire filaments. In high density plasmas (>10{sup 12} cm{sup −3}), hexaboride emitters are required because tungsten filaments cannot be heated to sufficient emission without component failure. A resistively heated emissive probe with a cerium hexaboride, CeB{sub 6}, emitter has been developed to work in plasma densities up to 10{sup 13} cm{sup −3}. To show functionality, three spatial profiles of V{sub p} are compared using the emissive probe, a cold floating probe, and a swept probe inside a plasma containing regions with and without current. The swept probe and emissive probe agree well across the profile while the floating cold probe fails in the current carrying region.

Authors:
; ; ;  [1]
  1. Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States)
Publication Date:
OSTI Identifier:
22392497
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 86; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; 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; EMISSION; FILAMENTS; PLASMA DENSITY; PROBES; SPACE CHARGE; TUNGSTEN; WIRES

Citation Formats

Martin, M. J., E-mail: mmartin@physics.ucla.edu, Bonde, J., Gekelman, W., and Pribyl, P. A resistively heated CeB{sub 6} emissive probe. United States: N. p., 2015. Web. doi:10.1063/1.4921838.
Martin, M. J., E-mail: mmartin@physics.ucla.edu, Bonde, J., Gekelman, W., & Pribyl, P. A resistively heated CeB{sub 6} emissive probe. United States. doi:10.1063/1.4921838.
Martin, M. J., E-mail: mmartin@physics.ucla.edu, Bonde, J., Gekelman, W., and Pribyl, P. Fri . "A resistively heated CeB{sub 6} emissive probe". United States. doi:10.1063/1.4921838.
@article{osti_22392497,
title = {A resistively heated CeB{sub 6} emissive probe},
author = {Martin, M. J., E-mail: mmartin@physics.ucla.edu and Bonde, J. and Gekelman, W. and Pribyl, P.},
abstractNote = {The plasma potential, V{sub p}, is a key quantity in experimental plasma physics. Its spatial gradients directly yield the electrostatic field present. Emissive probes operating under space-charge limited emission conditions float close to V{sub p} even under time-varying conditions. Throughout their long history in plasma physics, they have mostly been constructed with resistively heated tungsten wire filaments. In high density plasmas (>10{sup 12} cm{sup −3}), hexaboride emitters are required because tungsten filaments cannot be heated to sufficient emission without component failure. A resistively heated emissive probe with a cerium hexaboride, CeB{sub 6}, emitter has been developed to work in plasma densities up to 10{sup 13} cm{sup −3}. To show functionality, three spatial profiles of V{sub p} are compared using the emissive probe, a cold floating probe, and a swept probe inside a plasma containing regions with and without current. The swept probe and emissive probe agree well across the profile while the floating cold probe fails in the current carrying region.},
doi = {10.1063/1.4921838},
journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 5,
volume = 86,
place = {United States},
year = {2015},
month = {5}
}