Observation of D2 molecule line emission after massive D2 injection into runaway electron plateaus in DIII-D

E. M. Hollmann; J. L. Herfindal; A. McLean; A. Yu Pigarov; D. Shiraki; R. S. Wilcox

doi:10.1063/5.0162644

Observation of D₂ molecule line emission after massive D₂ injection into runaway electron plateaus in DIII-D

E. M. Hollmann, J. L. Herfindal, A. McLean, A. Yu Pigarov, D. Shiraki, R. S. Wilcox

Advanced Tokamak Physics

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

Molecular deuterium line emission is observed in both the visible and ultraviolet (UV) wavelength ranges after massive (> 100 Torr-L) injection of D 2 gas into post-disruption runaway electron (RE) dominated plasmas in the DIII-D tokamak. D 2 UV line emission is found to be the dominant source of radiated power, surpassing D Lyα. Interpretive modeling with a collisional-radiative model (CRM) indicates that D 2 radiation surpasses D radiation because Lyα is strongly trapped, while D 2 UV lines are mostly untrapped. The CRM also indicates that the D 2 line emission is completely dominated by RE impact (rather than thermal electron impact), so the D 2 line emission can serve as a good diagnostic for the spatial localization of REs. Analysis of D 2 visible lines indicates that the D 2 molecules in the plasma are thermally equilibrated with the background plasma, with vibrational, rotational, and kinetic temperatures all near 0.3 eV. D 2 spectroscopy therefore serves as a convenient diagnostic of background plasma temperature. Measurement of D 2 radiated power also appears to serve as a useful diagnostic for constraining neutral transport modeling.

Original language	English
Article number	103302
Journal	Physics of Plasmas
Volume	30
Issue number	10
DOIs	https://doi.org/10.1063/5.0162644
State	Published - Oct 1 2023

Funding

This work was supported in part by the U.S. Department of Energy under DE-FG02-07ER54917, DE-AC05-00OR22725, DE-FC02-04ER54698, DE-FG02-04ER54744, and DE-AC52-07NA27344. Technical support of L. Chousal is gratefully acknowledged, as is the diagnostic operation support of A. Moser, F. Glass, and M. Van Zeeland, and the assistance of T. O'Gorman with TS data analysis.

Funders	Funder number
U.S. Department of Energy	DE-AC05-00OR22725, DE-FC02-04ER54698, DE-FG02-04ER54744, DE-AC52-07NA27344, DE-FG02-07ER54917

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Cite this

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title = "Observation of D2 molecule line emission after massive D2 injection into runaway electron plateaus in DIII-D",

abstract = "Molecular deuterium line emission is observed in both the visible and ultraviolet (UV) wavelength ranges after massive (> 100 Torr-L) injection of D 2 gas into post-disruption runaway electron (RE) dominated plasmas in the DIII-D tokamak. D 2 UV line emission is found to be the dominant source of radiated power, surpassing D Lyα. Interpretive modeling with a collisional-radiative model (CRM) indicates that D 2 radiation surpasses D radiation because Lyα is strongly trapped, while D 2 UV lines are mostly untrapped. The CRM also indicates that the D 2 line emission is completely dominated by RE impact (rather than thermal electron impact), so the D 2 line emission can serve as a good diagnostic for the spatial localization of REs. Analysis of D 2 visible lines indicates that the D 2 molecules in the plasma are thermally equilibrated with the background plasma, with vibrational, rotational, and kinetic temperatures all near 0.3 eV. D 2 spectroscopy therefore serves as a convenient diagnostic of background plasma temperature. Measurement of D 2 radiated power also appears to serve as a useful diagnostic for constraining neutral transport modeling.",

author = "Hollmann, {E. M.} and Herfindal, {J. L.} and A. McLean and Pigarov, {A. Yu} and D. Shiraki and Wilcox, {R. S.}",

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doi = "10.1063/5.0162644",

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T1 - Observation of D2 molecule line emission after massive D2 injection into runaway electron plateaus in DIII-D

AU - Hollmann, E. M.

AU - Herfindal, J. L.

AU - McLean, A.

AU - Pigarov, A. Yu

AU - Shiraki, D.

AU - Wilcox, R. S.

PY - 2023/10/1

Y1 - 2023/10/1

N2 - Molecular deuterium line emission is observed in both the visible and ultraviolet (UV) wavelength ranges after massive (> 100 Torr-L) injection of D 2 gas into post-disruption runaway electron (RE) dominated plasmas in the DIII-D tokamak. D 2 UV line emission is found to be the dominant source of radiated power, surpassing D Lyα. Interpretive modeling with a collisional-radiative model (CRM) indicates that D 2 radiation surpasses D radiation because Lyα is strongly trapped, while D 2 UV lines are mostly untrapped. The CRM also indicates that the D 2 line emission is completely dominated by RE impact (rather than thermal electron impact), so the D 2 line emission can serve as a good diagnostic for the spatial localization of REs. Analysis of D 2 visible lines indicates that the D 2 molecules in the plasma are thermally equilibrated with the background plasma, with vibrational, rotational, and kinetic temperatures all near 0.3 eV. D 2 spectroscopy therefore serves as a convenient diagnostic of background plasma temperature. Measurement of D 2 radiated power also appears to serve as a useful diagnostic for constraining neutral transport modeling.

AB - Molecular deuterium line emission is observed in both the visible and ultraviolet (UV) wavelength ranges after massive (> 100 Torr-L) injection of D 2 gas into post-disruption runaway electron (RE) dominated plasmas in the DIII-D tokamak. D 2 UV line emission is found to be the dominant source of radiated power, surpassing D Lyα. Interpretive modeling with a collisional-radiative model (CRM) indicates that D 2 radiation surpasses D radiation because Lyα is strongly trapped, while D 2 UV lines are mostly untrapped. The CRM also indicates that the D 2 line emission is completely dominated by RE impact (rather than thermal electron impact), so the D 2 line emission can serve as a good diagnostic for the spatial localization of REs. Analysis of D 2 visible lines indicates that the D 2 molecules in the plasma are thermally equilibrated with the background plasma, with vibrational, rotational, and kinetic temperatures all near 0.3 eV. D 2 spectroscopy therefore serves as a convenient diagnostic of background plasma temperature. Measurement of D 2 radiated power also appears to serve as a useful diagnostic for constraining neutral transport modeling.

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