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

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

Journal Article · Mon Nov 30 00:00:00 EST 2020 · Nuclear Fusion

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

^[1]; Shiraki, D. ^[2]; Baylor, L. ^[2]; Bykov, I. ^[3]; ^[4]; Golovkin, I. ^[5]; ^[2]; ^[4]; McLean, A. ^[6]; Moyer, R. A. ^[3]; O’Gorman, T. ^[4]; Parks, P. B. ^[4]; Popović, Ž. ^[3]

Univ. of California, San Diego, La Jolla, CA (United States); General Atomics, Energy & Advanced Concepts, DIII-D
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Univ. of California, San Diego, La Jolla, CA (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.

View Accepted Manuscript (DOE)

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

OSTI ID:: 1730928

Alternate ID(s):: OSTI ID: 2320366
OSTI ID: 23129576

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

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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