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Title: The surface eroding thermocouple for fast heat flux measurement in DIII-D

Abstract

A novel type of surface eroding thermocouple (SETC) has been tested and demonstrated in the small angle slot (SAS) divertor of DIII-D for fast local heat flux measurements. The thermojunction of the SETC is formed between two thin (10 μm) ribbons, which are filed over to create microfiber junctions. These thermocouples are able to be exposed directly to the plasma at surface temperatures exceeding 2000 °C and are capable of sub-10 ms time resolution. Before installation in SAS, the SETCs were exposed in the lower DIII-D divertor during L-mode and H-mode discharges, from which results are presented. In preliminary tests, SETCs proved to be a qualified diagnostic to accurately measure both the intra-edge localized mode (ELM) and inter-ELM heat flux during H-mode shots with high frequency ELMs (hundreds of Hz) and to resolve heat flux profiles during strike point sweeps. The heat fluxes measured by using SETCs are consistent with the heat fluxes measured by using IR cameras and Langmuir probes. These new diagnostic capabilities will complement the existing IR camera measurements and will be of particularly significant value to measure surface heat flux in the SAS divertor or other regions where the IR camera lacks line of sight.

Authors:
 [1]; ORCiD logo [2];  [3];  [4];  [5];  [6];  [7];  [7]; ORCiD logo [8];  [6];  [6]
+ Show Author Affiliations
  1. Univ. of Tennessee, Knoxville, TN (United States)
  2. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  4. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  5. Univ. of California, San Diego, CA (United States)
  6. General Atomics, San Diego, CA (United States)
  7. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  8. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1543206
Alternate Identifier(s):
OSTI ID: 1476689; OSTI ID: 1660785
Grant/Contract Number:  
AC05-00OR22725; SC0016318; FC02-04ER54698; FG02-07ER54917; NA0003525; AC52-07NA27344; SC0019256
Resource Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 89; Journal Issue: 10; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Ren, J., Donovan, David C., Watkins, J. G., Wang, Huiqian, Rudakov, D. L., Murphy, Christopher, McLean, A. G., Lasnier, C. J., Unterberg, Ezekial, Thomas, D. M., and Boivin, R. L. The surface eroding thermocouple for fast heat flux measurement in DIII-D. United States: N. p., 2018. Web. doi:10.1063/1.5038677.
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Ren, J., Donovan, David C., Watkins, J. G., Wang, Huiqian, Rudakov, D. L., Murphy, Christopher, McLean, A. G., Lasnier, C. J., Unterberg, Ezekial, Thomas, D. M., & Boivin, R. L. The surface eroding thermocouple for fast heat flux measurement in DIII-D. United States. https://doi.org/10.1063/1.5038677
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Ren, J., Donovan, David C., Watkins, J. G., Wang, Huiqian, Rudakov, D. L., Murphy, Christopher, McLean, A. G., Lasnier, C. J., Unterberg, Ezekial, Thomas, D. M., and Boivin, R. L. Mon . "The surface eroding thermocouple for fast heat flux measurement in DIII-D". United States. https://doi.org/10.1063/1.5038677. https://www.osti.gov/servlets/purl/1543206.
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@article{osti_1543206,
title = {The surface eroding thermocouple for fast heat flux measurement in DIII-D},
author = {Ren, J. and Donovan, David C. and Watkins, J. G. and Wang, Huiqian and Rudakov, D. L. and Murphy, Christopher and McLean, A. G. and Lasnier, C. J. and Unterberg, Ezekial and Thomas, D. M. and Boivin, R. L.},
abstractNote = {A novel type of surface eroding thermocouple (SETC) has been tested and demonstrated in the small angle slot (SAS) divertor of DIII-D for fast local heat flux measurements. The thermojunction of the SETC is formed between two thin (10 μm) ribbons, which are filed over to create microfiber junctions. These thermocouples are able to be exposed directly to the plasma at surface temperatures exceeding 2000 °C and are capable of sub-10 ms time resolution. Before installation in SAS, the SETCs were exposed in the lower DIII-D divertor during L-mode and H-mode discharges, from which results are presented. In preliminary tests, SETCs proved to be a qualified diagnostic to accurately measure both the intra-edge localized mode (ELM) and inter-ELM heat flux during H-mode shots with high frequency ELMs (hundreds of Hz) and to resolve heat flux profiles during strike point sweeps. The heat fluxes measured by using SETCs are consistent with the heat fluxes measured by using IR cameras and Langmuir probes. These new diagnostic capabilities will complement the existing IR camera measurements and will be of particularly significant value to measure surface heat flux in the SAS divertor or other regions where the IR camera lacks line of sight.},
doi = {10.1063/1.5038677},
journal = {Review of Scientific Instruments},
number = 10,
volume = 89,
place = {United States},
year = {2018},
month = {10}
}
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Journal Article:
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Publisher's Version of Record
https://doi.org/10.1063/1.5038677
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Figures / Tables:

Figure 1 Figure 1: Schematic diagram of (a) a traditional thermocouple and (b) a structure representation of a surface eroding thermocouple. Ribbons A and B are dissimilar materials that create a thermal voltage when joined.
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Works referenced in this record:

Plasma detachment in divertor tokamaks
journal, February 2018

SlimCS—compact low aspect ratio DEMO reactor with reduced-size central solenoid
journal, July 2007

Analysis of a multi-machine database on divertor heat fluxes
journal, May 2012

  • Makowski, M. A.; Elder, D.; Gray, T. K.
  • Physics of Plasmas, Vol. 19, Issue 5
  • DOI: 10.1063/1.4710517

D III-D divertor target heat flux measurements during ohmic and neutral beam heating
journal, May 1988

Chapter 10: First Wall and Operational Diagnostics
journal, February 2008

  • Lasnier, C. J.; Allen, S. L.; Boedo, J. A.
  • Fusion Science and Technology, Vol. 53, Issue 2
  • DOI: 10.13182/fst08-a1682

Surface thermocouples for measurement of pulsed heat flux in the divertor of the Alcator C-Mod tokamak
journal, March 2012

  • Brunner, D.; LaBombard, B.
  • Review of Scientific Instruments, Vol. 83, Issue 3
  • DOI: 10.1063/1.3689770

Feedback system for divertor impurity seeding based on real-time measurements of surface heat flux in the Alcator C-Mod tokamak
journal, February 2016

  • Brunner, D.; Burke, W.; Kuang, A. Q.
  • Review of Scientific Instruments, Vol. 87, Issue 2
  • DOI: 10.1063/1.4941047

Calorimeter probe for the DIII-D divertor
journal, March 2003

  • Watkins, J. G.; Lasnier, C. J.; Whyte, D. G.
  • Review of Scientific Instruments, Vol. 74, Issue 3
  • DOI: 10.1063/1.1527241

Type-I ELM substructure on the divertor target plates in ASDEX Upgrade
journal, May 2005

Experimental measurements of the particle flux and sheath power transmission factor profiles in the divertor of DIII-D
journal, July 2013

Recent sheath physics studies on DIII-D
journal, August 2015

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    Figures / Tables found in this record:

    Figure 1 (p. 10)figure
    Figure 2 (p. 10)figure
    Figure 3 (p. 11)figure
    Figure 4 (p. 11)figure
    Figure 5 (p. 12)figure
    Figure 6 (p. 12)figure
    Figure 7 (p. 12)figure
    Figure 8 (p. 13)figure
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