Spectroscopic investigation of N and Ne seeded induced detachment in JET ITER-like wall L-modes combining experiment and EDGE2D modeling

B. Lomanowski, M. Carr, A. Field, M. Groth, A.E. Jaervinen, C. Lowry, A.G. Meigs, S. Menmuir, M. O'Mullane, M.L. Reinke, C.K. Stavrou, S. Wiesen

Research output: Contribution to journalArticle

Abstract

Modeling and experimental investigation of the distribution of seeded impurities and their influence on divertor detachment in all-metal tokamaks is critical for developing reactor-scale exhaust scenarios. In this work, the degree and operating space for Ne and N impurity seeded induced detachment in JET with ITER-like wall (JET-ILW) L-mode discharges is shown to be regulated by the combination of i) the local radiative dissipation in the low-field side divertor; and ii) the incursion of the ionization front towards the X-point with increased impurity seeding. Using a quantitative spectroscopic approach, it is shown that the net particle balance at the low-field side target is dominated by a marked decrease in the ionization source between the X-point and the target with increased N and Ne seeding, and only a marginal increase in the volume recombination rate. With increased seeding, the local radiated power dissipation (N only) and reduction in the power crossing the separatrix (both nitrogen and neon) leads to a reduction in the low-field side target Te. Consequently, the incursion of the ionization front away from a region of enhanced ionization rate caused by high Lyman series opacity at the outer target leads to a steep decrease of the outer target ion flux. In contrast to experiment, EDGE2D-EIRENE simulations using optically thin divertor plasma assumptions show a larger impact of volume recombination and a factor of two shortfall in the low-field side divertor ne. A detailed assessment of opacity effects using the EIRENE photon transport module is recommended.

LanguageEnglish
Article number100676
Number of pages10
JournalNuclear Materials and Energy
Volume20
Early online date16 Apr 2019
DOIs
Publication statusPublished - 31 Aug 2019

Fingerprint

detachment
Ionization
Opacity
Impurities
inoculation
ionization
Neon
opacity
impurities
Experiments
Ion sources
dissipation
Energy dissipation
Nitrogen
Photons
Metals
Ions
Fluxes
Plasmas
neon

Keywords

  • detachment evolution
  • divertor spectroscopy
  • EDGE2D-EIRENE
  • impurity seeded detachment
  • JET-ILW

Cite this

Lomanowski, B. ; Carr, M. ; Field, A. ; Groth, M. ; Jaervinen, A.E. ; Lowry, C. ; Meigs, A.G. ; Menmuir, S. ; O'Mullane, M. ; Reinke, M.L. ; Stavrou, C.K. ; Wiesen, S. / Spectroscopic investigation of N and Ne seeded induced detachment in JET ITER-like wall L-modes combining experiment and EDGE2D modeling. In: Nuclear Materials and Energy. 2019 ; Vol. 20.
@article{b68c9c37dbb948969fd6596f030634c4,
title = "Spectroscopic investigation of N and Ne seeded induced detachment in JET ITER-like wall L-modes combining experiment and EDGE2D modeling",
abstract = "Modeling and experimental investigation of the distribution of seeded impurities and their influence on divertor detachment in all-metal tokamaks is critical for developing reactor-scale exhaust scenarios. In this work, the degree and operating space for Ne and N impurity seeded induced detachment in JET with ITER-like wall (JET-ILW) L-mode discharges is shown to be regulated by the combination of i) the local radiative dissipation in the low-field side divertor; and ii) the incursion of the ionization front towards the X-point with increased impurity seeding. Using a quantitative spectroscopic approach, it is shown that the net particle balance at the low-field side target is dominated by a marked decrease in the ionization source between the X-point and the target with increased N and Ne seeding, and only a marginal increase in the volume recombination rate. With increased seeding, the local radiated power dissipation (N only) and reduction in the power crossing the separatrix (both nitrogen and neon) leads to a reduction in the low-field side target Te. Consequently, the incursion of the ionization front away from a region of enhanced ionization rate caused by high Lyman series opacity at the outer target leads to a steep decrease of the outer target ion flux. In contrast to experiment, EDGE2D-EIRENE simulations using optically thin divertor plasma assumptions show a larger impact of volume recombination and a factor of two shortfall in the low-field side divertor ne. A detailed assessment of opacity effects using the EIRENE photon transport module is recommended.",
keywords = "detachment evolution, divertor spectroscopy, EDGE2D-EIRENE, impurity seeded detachment, JET-ILW",
author = "B. Lomanowski and M. Carr and A. Field and M. Groth and A.E. Jaervinen and C. Lowry and A.G. Meigs and S. Menmuir and M. O'Mullane and M.L. Reinke and C.K. Stavrou and S. Wiesen",
year = "2019",
month = "8",
day = "31",
doi = "10.1016/j.nme.2019.100676",
language = "English",
volume = "20",
journal = "Nuclear Materials and Energy",
issn = "2352-1791",

}

Lomanowski, B, Carr, M, Field, A, Groth, M, Jaervinen, AE, Lowry, C, Meigs, AG, Menmuir, S, O'Mullane, M, Reinke, ML, Stavrou, CK & Wiesen, S 2019, 'Spectroscopic investigation of N and Ne seeded induced detachment in JET ITER-like wall L-modes combining experiment and EDGE2D modeling' Nuclear Materials and Energy, vol. 20, 100676. https://doi.org/10.1016/j.nme.2019.100676

Spectroscopic investigation of N and Ne seeded induced detachment in JET ITER-like wall L-modes combining experiment and EDGE2D modeling. / Lomanowski, B.; Carr, M.; Field, A.; Groth, M.; Jaervinen, A.E.; Lowry, C.; Meigs, A.G.; Menmuir, S.; O'Mullane, M.; Reinke, M.L.; Stavrou, C.K.; Wiesen, S.

In: Nuclear Materials and Energy, Vol. 20, 100676, 31.08.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Spectroscopic investigation of N and Ne seeded induced detachment in JET ITER-like wall L-modes combining experiment and EDGE2D modeling

AU - Lomanowski, B.

AU - Carr, M.

AU - Field, A.

AU - Groth, M.

AU - Jaervinen, A.E.

AU - Lowry, C.

AU - Meigs, A.G.

AU - Menmuir, S.

AU - O'Mullane, M.

AU - Reinke, M.L.

AU - Stavrou, C.K.

AU - Wiesen, S.

PY - 2019/8/31

Y1 - 2019/8/31

N2 - Modeling and experimental investigation of the distribution of seeded impurities and their influence on divertor detachment in all-metal tokamaks is critical for developing reactor-scale exhaust scenarios. In this work, the degree and operating space for Ne and N impurity seeded induced detachment in JET with ITER-like wall (JET-ILW) L-mode discharges is shown to be regulated by the combination of i) the local radiative dissipation in the low-field side divertor; and ii) the incursion of the ionization front towards the X-point with increased impurity seeding. Using a quantitative spectroscopic approach, it is shown that the net particle balance at the low-field side target is dominated by a marked decrease in the ionization source between the X-point and the target with increased N and Ne seeding, and only a marginal increase in the volume recombination rate. With increased seeding, the local radiated power dissipation (N only) and reduction in the power crossing the separatrix (both nitrogen and neon) leads to a reduction in the low-field side target Te. Consequently, the incursion of the ionization front away from a region of enhanced ionization rate caused by high Lyman series opacity at the outer target leads to a steep decrease of the outer target ion flux. In contrast to experiment, EDGE2D-EIRENE simulations using optically thin divertor plasma assumptions show a larger impact of volume recombination and a factor of two shortfall in the low-field side divertor ne. A detailed assessment of opacity effects using the EIRENE photon transport module is recommended.

AB - Modeling and experimental investigation of the distribution of seeded impurities and their influence on divertor detachment in all-metal tokamaks is critical for developing reactor-scale exhaust scenarios. In this work, the degree and operating space for Ne and N impurity seeded induced detachment in JET with ITER-like wall (JET-ILW) L-mode discharges is shown to be regulated by the combination of i) the local radiative dissipation in the low-field side divertor; and ii) the incursion of the ionization front towards the X-point with increased impurity seeding. Using a quantitative spectroscopic approach, it is shown that the net particle balance at the low-field side target is dominated by a marked decrease in the ionization source between the X-point and the target with increased N and Ne seeding, and only a marginal increase in the volume recombination rate. With increased seeding, the local radiated power dissipation (N only) and reduction in the power crossing the separatrix (both nitrogen and neon) leads to a reduction in the low-field side target Te. Consequently, the incursion of the ionization front away from a region of enhanced ionization rate caused by high Lyman series opacity at the outer target leads to a steep decrease of the outer target ion flux. In contrast to experiment, EDGE2D-EIRENE simulations using optically thin divertor plasma assumptions show a larger impact of volume recombination and a factor of two shortfall in the low-field side divertor ne. A detailed assessment of opacity effects using the EIRENE photon transport module is recommended.

KW - detachment evolution

KW - divertor spectroscopy

KW - EDGE2D-EIRENE

KW - impurity seeded detachment

KW - JET-ILW

UR - http://www.scopus.com/inward/record.url?scp=85070625350&partnerID=8YFLogxK

U2 - 10.1016/j.nme.2019.100676

DO - 10.1016/j.nme.2019.100676

M3 - Article

VL - 20

JO - Nuclear Materials and Energy

T2 - Nuclear Materials and Energy

JF - Nuclear Materials and Energy

SN - 2352-1791

M1 - 100676

ER -