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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 can be exposed directly to the plasma at surface temperatures exceeding 2000 °C and are capable of sub-10 ms time resolution. Prior to 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]
  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)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1543206
Alternate Identifier(s):
OSTI ID: 1476689
Grant/Contract Number:  
AC05-00OR22725; SC0016318; FC02-04ER54698; FG02-07ER54917; NA0003525; AC52-07NA27344
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.
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. doi:10.1063/1.5038677.
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. doi:10.1063/1.5038677. https://www.osti.gov/servlets/purl/1543206.
@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 can be exposed directly to the plasma at surface temperatures exceeding 2000 °C and are capable of sub-10 ms time resolution. Prior to 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}
}

Journal Article:
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