Dissociative recombination and electron-impact de-excitation in CH photon emission under ITER divertor-relevant plasma conditions

G.A. Swaaij, van, K.E. Bystrov, D. Borodin, A. Kirschner, L.B. Vegt, van der, G.J. Rooij, van, G.C. De Temmerman, W.J. Goedheer

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Abstract

For understanding carbon erosion and redeposition in nuclear fusion devices, it is important to understand the transport and chemical break-up of hydrocarbon molecules in edge plasmas, often diagnosed by emission of the CH A 2¿–X 2¿ Gerö band around 430 nm. The CH A-level can be excited either by electron-impact (EI) or by dissociative recombination (DR) of hydrocarbon ions. These processes were included in the 3D Monte Carlo impurity transport code ERO. A series of methane injection experiments was performed in the high-density, low-temperature linear plasma generator Pilot-PSI, and simulated emission intensity profiles were benchmarked against these experiments. It was confirmed that excitation by DR dominates at Te <1.5 eV. The results indicate that the fraction of DR events that lead to a CH radical in the A-level and consequent photon emission is at least 10%. Additionally, quenching of the excited CH radicals by EI de-excitation was included in the modeling. This quenching is shown to be significant: depending on the electron density, it reduces the effective CH emission by a factor of 1.4 at ne = 1.3 × 1020 m-3, to 2.8 at ne = 9.3 × 1020 m-3. Its inclusion significantly improved agreement between experiment and modeling.
LanguageEnglish
Article number095013
Pages095013-1/9
Number of pages9
JournalPlasma Physics and Controlled Fusion
Volume54
Issue number9
DOIs
StatePublished - 2012

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electron impact
Photons
methylidyne
Plasmas
Electrons
Quenching
photons
Hydrocarbons
excitation
Experiments
hydrocarbons
quenching
Carrier concentration
Erosion
Methane
Fusion reactions
plasma generators
Impurities
Molecules
Carbon

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Swaaij, van, G. A., Bystrov, K. E., Borodin, D., Kirschner, A., Vegt, van der, L. B., Rooij, van, G. J., ... Goedheer, W. J. (2012). Dissociative recombination and electron-impact de-excitation in CH photon emission under ITER divertor-relevant plasma conditions. Plasma Physics and Controlled Fusion, 54(9), 095013-1/9. [095013]. DOI: 10.1088/0741-3335/54/9/095013
Swaaij, van, G.A. ; Bystrov, K.E. ; Borodin, D. ; Kirschner, A. ; Vegt, van der, L.B. ; Rooij, van, G.J. ; De Temmerman, G.C. ; Goedheer, W.J./ Dissociative recombination and electron-impact de-excitation in CH photon emission under ITER divertor-relevant plasma conditions. In: Plasma Physics and Controlled Fusion. 2012 ; Vol. 54, No. 9. pp. 095013-1/9
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abstract = "For understanding carbon erosion and redeposition in nuclear fusion devices, it is important to understand the transport and chemical break-up of hydrocarbon molecules in edge plasmas, often diagnosed by emission of the CH A 2¿–X 2¿ Ger{\"o} band around 430 nm. The CH A-level can be excited either by electron-impact (EI) or by dissociative recombination (DR) of hydrocarbon ions. These processes were included in the 3D Monte Carlo impurity transport code ERO. A series of methane injection experiments was performed in the high-density, low-temperature linear plasma generator Pilot-PSI, and simulated emission intensity profiles were benchmarked against these experiments. It was confirmed that excitation by DR dominates at Te <1.5 eV. The results indicate that the fraction of DR events that lead to a CH radical in the A-level and consequent photon emission is at least 10{\%}. Additionally, quenching of the excited CH radicals by EI de-excitation was included in the modeling. This quenching is shown to be significant: depending on the electron density, it reduces the effective CH emission by a factor of 1.4 at ne = 1.3 × 1020 m-3, to 2.8 at ne = 9.3 × 1020 m-3. Its inclusion significantly improved agreement between experiment and modeling.",
author = "{Swaaij, van}, G.A. and K.E. Bystrov and D. Borodin and A. Kirschner and {Vegt, van der}, L.B. and {Rooij, van}, G.J. and {De Temmerman}, G.C. and W.J. Goedheer",
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Swaaij, van, GA, Bystrov, KE, Borodin, D, Kirschner, A, Vegt, van der, LB, Rooij, van, GJ, De Temmerman, GC & Goedheer, WJ 2012, 'Dissociative recombination and electron-impact de-excitation in CH photon emission under ITER divertor-relevant plasma conditions' Plasma Physics and Controlled Fusion, vol. 54, no. 9, 095013, pp. 095013-1/9. DOI: 10.1088/0741-3335/54/9/095013

Dissociative recombination and electron-impact de-excitation in CH photon emission under ITER divertor-relevant plasma conditions. / Swaaij, van, G.A.; Bystrov, K.E.; Borodin, D.; Kirschner, A.; Vegt, van der, L.B.; Rooij, van, G.J.; De Temmerman, G.C.; Goedheer, W.J.

In: Plasma Physics and Controlled Fusion, Vol. 54, No. 9, 095013, 2012, p. 095013-1/9.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Dissociative recombination and electron-impact de-excitation in CH photon emission under ITER divertor-relevant plasma conditions

AU - Swaaij, van,G.A.

AU - Bystrov,K.E.

AU - Borodin,D.

AU - Kirschner,A.

AU - Vegt, van der,L.B.

AU - Rooij, van,G.J.

AU - De Temmerman,G.C.

AU - Goedheer,W.J.

PY - 2012

Y1 - 2012

N2 - For understanding carbon erosion and redeposition in nuclear fusion devices, it is important to understand the transport and chemical break-up of hydrocarbon molecules in edge plasmas, often diagnosed by emission of the CH A 2¿–X 2¿ Gerö band around 430 nm. The CH A-level can be excited either by electron-impact (EI) or by dissociative recombination (DR) of hydrocarbon ions. These processes were included in the 3D Monte Carlo impurity transport code ERO. A series of methane injection experiments was performed in the high-density, low-temperature linear plasma generator Pilot-PSI, and simulated emission intensity profiles were benchmarked against these experiments. It was confirmed that excitation by DR dominates at Te <1.5 eV. The results indicate that the fraction of DR events that lead to a CH radical in the A-level and consequent photon emission is at least 10%. Additionally, quenching of the excited CH radicals by EI de-excitation was included in the modeling. This quenching is shown to be significant: depending on the electron density, it reduces the effective CH emission by a factor of 1.4 at ne = 1.3 × 1020 m-3, to 2.8 at ne = 9.3 × 1020 m-3. Its inclusion significantly improved agreement between experiment and modeling.

AB - For understanding carbon erosion and redeposition in nuclear fusion devices, it is important to understand the transport and chemical break-up of hydrocarbon molecules in edge plasmas, often diagnosed by emission of the CH A 2¿–X 2¿ Gerö band around 430 nm. The CH A-level can be excited either by electron-impact (EI) or by dissociative recombination (DR) of hydrocarbon ions. These processes were included in the 3D Monte Carlo impurity transport code ERO. A series of methane injection experiments was performed in the high-density, low-temperature linear plasma generator Pilot-PSI, and simulated emission intensity profiles were benchmarked against these experiments. It was confirmed that excitation by DR dominates at Te <1.5 eV. The results indicate that the fraction of DR events that lead to a CH radical in the A-level and consequent photon emission is at least 10%. Additionally, quenching of the excited CH radicals by EI de-excitation was included in the modeling. This quenching is shown to be significant: depending on the electron density, it reduces the effective CH emission by a factor of 1.4 at ne = 1.3 × 1020 m-3, to 2.8 at ne = 9.3 × 1020 m-3. Its inclusion significantly improved agreement between experiment and modeling.

U2 - 10.1088/0741-3335/54/9/095013

DO - 10.1088/0741-3335/54/9/095013

M3 - Article

VL - 54

SP - 095013-1/9

JO - Plasma Physics and Controlled Fusion

T2 - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

SN - 0741-3335

IS - 9

M1 - 095013

ER -