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Title: Observation of non-thermal electron formation during the thermal quench of shattered pellet injection shutdowns in DIII-D

Abstract

Formation of non-thermal (hot) electrons is studied during the thermal quench of shattered pellet injection (SPI) discharge shutdowns in the DIII-D tokamak. Both pure neon and mixed neon/deuterium shutdowns are studied. High-energy radiation (SXR and EUV) brightness levels show indications of non-thermal electron formation during the TQ. The non-thermal densities are of order 1018 m–3 and non-thermal temperatures are estimated to be of order 10 keV. The non-thermal electrons appear to be mostly lost during the subsequent current quench, as no signal of relativistic runaway electrons is typically seen at the end of the current quench. In conclusion, the non-thermals appear to have an effect on the deposition profile of the SPI pellets, especially at the end of the TQ, due to increased pellet ablation.

Authors:
ORCiD logo [1];  [2];  [2];  [1]; ORCiD logo [3];  [4]; ORCiD logo [2]; ORCiD logo [3];  [5];  [1];  [3];  [3];  [1]
  1. Univ. of California, San Diego, La Jolla, CA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Prism Computational Sciences, Madison, WI (United States)
  5. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1730928
Grant/Contract Number:  
FC02-04ER54698; FG02-07ER54917; AC05-00OR22725; AC52-07NA27344; FG02-04ER54744; AC05-06OR23100
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 61; Journal Issue: 1; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Tokamak; disruptions; shattered pellet injection; runaway electrons

Citation Formats

Hollmann, E. M., Shiraki, D., Baylor, L., Bykov, I., Eidietis, N. W., Golovkin, I., Herfindal, J. L., Lvovskiy, A., McLean, A., Moyer, R. A., O’Gorman, T., Parks, P. B., and Popović, Ž.. Observation of non-thermal electron formation during the thermal quench of shattered pellet injection shutdowns in DIII-D. United States: N. p., 2020. Web. https://doi.org/10.1088/1741-4326/abc409.
Hollmann, E. M., Shiraki, D., Baylor, L., Bykov, I., Eidietis, N. W., Golovkin, I., Herfindal, J. L., Lvovskiy, A., McLean, A., Moyer, R. A., O’Gorman, T., Parks, P. B., & Popović, Ž.. Observation of non-thermal electron formation during the thermal quench of shattered pellet injection shutdowns in DIII-D. United States. https://doi.org/10.1088/1741-4326/abc409
Hollmann, E. M., Shiraki, D., Baylor, L., Bykov, I., Eidietis, N. W., Golovkin, I., Herfindal, J. L., Lvovskiy, A., McLean, A., Moyer, R. A., O’Gorman, T., Parks, P. B., and Popović, Ž.. Mon . "Observation of non-thermal electron formation during the thermal quench of shattered pellet injection shutdowns in DIII-D". United States. https://doi.org/10.1088/1741-4326/abc409. https://www.osti.gov/servlets/purl/1730928.
@article{osti_1730928,
title = {Observation of non-thermal electron formation during the thermal quench of shattered pellet injection shutdowns in DIII-D},
author = {Hollmann, E. M. and Shiraki, D. and Baylor, L. and Bykov, I. and Eidietis, N. W. and Golovkin, I. and Herfindal, J. L. and Lvovskiy, A. and McLean, A. and Moyer, R. A. and O’Gorman, T. and Parks, P. B. and Popović, Ž.},
abstractNote = {Formation of non-thermal (hot) electrons is studied during the thermal quench of shattered pellet injection (SPI) discharge shutdowns in the DIII-D tokamak. Both pure neon and mixed neon/deuterium shutdowns are studied. High-energy radiation (SXR and EUV) brightness levels show indications of non-thermal electron formation during the TQ. The non-thermal densities are of order 1018 m–3 and non-thermal temperatures are estimated to be of order 10 keV. The non-thermal electrons appear to be mostly lost during the subsequent current quench, as no signal of relativistic runaway electrons is typically seen at the end of the current quench. In conclusion, the non-thermals appear to have an effect on the deposition profile of the SPI pellets, especially at the end of the TQ, due to increased pellet ablation.},
doi = {10.1088/1741-4326/abc409},
journal = {Nuclear Fusion},
number = 1,
volume = 61,
place = {United States},
year = {2020},
month = {11}
}

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