High-resolution disruption halo current measurements using Langmuir probes in Alcator C-Mod

Tinguely, R. A.; Granetz, R. S.; Berg, A.; Kuang, A. Q.; Brunner, D.; LaBombard, B.

doi:10.7910/DVN/1IVQTC

Title: High-resolution disruption halo current measurements using Langmuir probes in Alcator C-Mod

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Abstract

Halo currents generated during disruptions on Alcator C-Mod have been measured with Langmuir “rail” probes. These rail probes are embedded in a lower outboard divertor module in a closely-spaced vertical (poloidal) array. The dense array provides detailed resolution of the spatial dependence (~1 cm spacing) of the halo current distribution in the plasma scrape-off region with high time resolution (400 kHz digitization rate). As the plasma limits on the outboard divertor plate, the contact point is clearly discernible in the halo current data (as an inversion of current) and moves vertically down the divertor plate on many disruptions. These data are consistent with filament reconstructions of the plasma boundary, from which the edge safety factor of the disrupting plasma can be calculated. Additionally, the halo current “footprint” on the divertor plate is obtained and related to the halo flux width. The voltage driving halo current and the effective resistance of the plasma region through which the halo current flows to reach the probes are also investigated. Estimations of the sheath resistance and halo region resistivity and temperature are given. This information could prove useful for modeling halo current dynamics.

Authors:

Tinguely, R. A.; Granetz, R. S.; Berg, A.; Kuang, A. Q.; Brunner, D.; LaBombard, B.

OSTI

Publication Date:: 2019-01-10

DOE Contract Number:: FC02-99ER54512

Research Org.:: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center

Sponsoring Org.:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY

OSTI Identifier:: 1881221

DOI:: https://doi.org/10.7910/DVN/1IVQTC

Citation Formats


                    Tinguely, R. A., Granetz, R. S., Berg, A., Kuang, A. Q., Brunner, D., and LaBombard, B. High-resolution disruption halo current measurements using Langmuir probes in Alcator C-Mod.  United States: N. p., 2019. 
        Web.  doi:10.7910/DVN/1IVQTC.

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                    Tinguely, R. A., Granetz, R. S., Berg, A., Kuang, A. Q., Brunner, D., & LaBombard, B. High-resolution disruption halo current measurements using Langmuir probes in Alcator C-Mod.  United States.  doi:https://doi.org/10.7910/DVN/1IVQTC

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                    Tinguely, R. A., Granetz, R. S., Berg, A., Kuang, A. Q., Brunner, D., and LaBombard, B. 2019.  
"High-resolution disruption halo current measurements using Langmuir probes in Alcator C-Mod".  United States.  doi:https://doi.org/10.7910/DVN/1IVQTC.  https://www.osti.gov/servlets/purl/1881221. Pub date:Thu Jan 10 23:00:00 EST 2019

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@article{osti_1881221,

  title        = {High-resolution disruption halo current measurements using Langmuir probes in Alcator C-Mod},

  author       = {Tinguely, R. A. and Granetz, R. S. and Berg, A. and Kuang, A. Q. and Brunner, D. and LaBombard, B.},

  abstractNote = {Halo currents generated during disruptions on Alcator C-Mod have been measured with Langmuir “rail” probes. These rail probes are embedded in a lower outboard divertor module in a closely-spaced vertical (poloidal) array. The dense array provides detailed resolution of the spatial dependence (~1 cm spacing) of the halo current distribution in the plasma scrape-off region with high time resolution (400 kHz digitization rate). As the plasma limits on the outboard divertor plate, the contact point is clearly discernible in the halo current data (as an inversion of current) and moves vertically down the divertor plate on many disruptions. These data are consistent with filament reconstructions of the plasma boundary, from which the edge safety factor of the disrupting plasma can be calculated. Additionally, the halo current “footprint” on the divertor plate is obtained and related to the halo flux width. The voltage driving halo current and the effective resistance of the plasma region through which the halo current flows to reach the probes are also investigated. Estimations of the sheath resistance and halo region resistivity and temperature are given. This information could prove useful for modeling halo current dynamics.},

  doi          = {10.7910/DVN/1IVQTC},

  journal      = {},

  number       = ,

  volume       = ,

  place        = {United States},

  year         = {2019},

  month        = {1}

}

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DOI: https://doi.org/10.7910/DVN/1IVQTC

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