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Title: The flush-mounted rail Langmuir probe array designed for the Alcator C-Mod vertical target plate divertor

Abstract

An array of flush-mounted and toroidally elongated Langmuir probes (henceforth called rail probes) have been specifically designed for the Alcator C-Mod’s vertical target plate divertor and operated over multiple campaigns. The “flush” geometry enables the tungsten electrodes to survive high heat flux conditions in which traditional “proud” tungsten electrodes suffer damage from melting. The toroidally elongated rail-like geometry reduces the influence of sheath expansion, which is an important effect to consider in the design and interpretation of flush-mounted Langmuir probes. The new rail probes successfully operated during C-Mod’s FY2015 and FY2016 experimental campaigns with no evidence of damage, despite being regularly subjected to heat flux densities parallel to the magnetic field exceeding ~1 GW m -2 for short periods of time. A comparison between rail and proud probe data indicates that sheath expansion effects were successfully mitigated by the rail design, extending the use of these Langmuir probes to incident magnetic field line angles as low as 0.5°.

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1527102
Alternate Identifier(s):
OSTI ID: 1434828
Grant/Contract Number:  
SC0014264; FC02-99ER54512
Resource Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 89; Journal Issue: 4; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Kuang, A. Q., Brunner, D., LaBombard, B., Leccacorvi, R., and Vieira, R. The flush-mounted rail Langmuir probe array designed for the Alcator C-Mod vertical target plate divertor. United States: N. p., 2018. Web. doi:10.1063/1.5023905.
Kuang, A. Q., Brunner, D., LaBombard, B., Leccacorvi, R., & Vieira, R. The flush-mounted rail Langmuir probe array designed for the Alcator C-Mod vertical target plate divertor. United States. doi:10.1063/1.5023905.
Kuang, A. Q., Brunner, D., LaBombard, B., Leccacorvi, R., and Vieira, R. Thu . "The flush-mounted rail Langmuir probe array designed for the Alcator C-Mod vertical target plate divertor". United States. doi:10.1063/1.5023905. https://www.osti.gov/servlets/purl/1527102.
@article{osti_1527102,
title = {The flush-mounted rail Langmuir probe array designed for the Alcator C-Mod vertical target plate divertor},
author = {Kuang, A. Q. and Brunner, D. and LaBombard, B. and Leccacorvi, R. and Vieira, R.},
abstractNote = {An array of flush-mounted and toroidally elongated Langmuir probes (henceforth called rail probes) have been specifically designed for the Alcator C-Mod’s vertical target plate divertor and operated over multiple campaigns. The “flush” geometry enables the tungsten electrodes to survive high heat flux conditions in which traditional “proud” tungsten electrodes suffer damage from melting. The toroidally elongated rail-like geometry reduces the influence of sheath expansion, which is an important effect to consider in the design and interpretation of flush-mounted Langmuir probes. The new rail probes successfully operated during C-Mod’s FY2015 and FY2016 experimental campaigns with no evidence of damage, despite being regularly subjected to heat flux densities parallel to the magnetic field exceeding ~1 GW m-2 for short periods of time. A comparison between rail and proud probe data indicates that sheath expansion effects were successfully mitigated by the rail design, extending the use of these Langmuir probes to incident magnetic field line angles as low as 0.5°.},
doi = {10.1063/1.5023905},
journal = {Review of Scientific Instruments},
number = 4,
volume = 89,
place = {United States},
year = {2018},
month = {4}
}

Journal Article:
Free Publicly Available Full Text
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Cited by: 2 works
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Figures / Tables:

FIG. 1 FIG. 1: Standard proud probe design used in Alcator C-Mod with a minimum 10° field line attack angle, $ψ$. These tungsten electrodes were not able to survive the divertor heat fluxes in C-Mod without melting, despite being exposed to plasma for typically less than 1 s.12 Reprinted with permission frommore » Kuang et al., Nucl. Mater. Energy 12, 1231–1235 (2017). Copyright 2017 Elsevier.« less

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