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

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.

doi:10.1088/1741-4326/abc409

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

Journal Article · 30 November 2020 · Nuclear Fusion

DOI: https://doi.org/10.1088/1741-4326/abc409 · OSTI ID:1730928

^[1]; Shiraki, D. ^[2]; Baylor, L. ^[2]; Bykov, I. ^[1];

^[3]; Golovkin, I. ^[4];

^[2];

^[3]; McLean, A. ^[5]; Moyer, R. A. ^[1]; O’Gorman, T. ^[3]; Parks, P. B. ^[3]; Popović, Ž. ^[1]

Univ. of California, San Diego, La Jolla, CA (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
General Atomics, San Diego, CA (United States)
Prism Computational Sciences, Madison, WI (United States)
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

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.

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Research Organization:: General Atomics, San Diego, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

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

Grant/Contract Number:: FC02-04ER54698; FG02-07ER54917; AC05-00OR22725; AC52-07NA27344; FG02-04ER54744; AC05-06OR23100

OSTI ID:: 1730928

Alternate ID(s):: OSTI ID: 2320366

Journal Information:: Nuclear Fusion, Vol. 61, Issue 1; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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