Emission intensities and line ratios from a fast neutral helium beam

J-W. Ahn, D. Craig, G. Fiksel, D.J. Den Hartog, J.K. Anderson, M.G. O'Mullane

Research output: Contribution to journalArticle

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Abstract

The emission intensities and line ratios from a fast neutral helium beam is investigated in the Madison Symmetric Torus (MST) [R. N. Dexter, D. W. Kerst, T. W. Lovell, S. C. Prager, and J. C. Sprott, Fusion Technol. 19, 131 1991]. Predicted He I line intensities and line ratios from a recently developed collisional-radiative model are compared with experiment. The intensity of singlet lines comes mostly (>95 from the contribution of the ground state population and is very weakly dependent on the initial metastable fraction at the observation point in the plasma core. On the other hand, the intensity of triplet lines is strongly affected by the local metastable state (2(1)S and 2(3)S) populations and the initial metastable fraction plays an important role in determining line intensities. The fraction of local metastable states can only be estimated by making use of electron temperature (T-e), electron density (n(e)), and effective ion charge (Z(eff)) profiles as inputs to the population balance equations. This leads triplet lines to be unusable for the investigation of their local plasma parameter dependence. The ratio of singlet lines at 667.8 nm and 492.2 nm (I-667/I-492) as well as the ratio of 667.8 nm and 501.6 nm lines (I-667/I-501) has been investigated for the dependence on T-e and n(e) both theoretically and experimentally. I-667/I-492 shows strong dependence on n(e) with weak sensitivity to T-e. Measurements and predictions agree quantitatively within a factor of 2. There has been no ratio of singlet lines identified to have strong enough T-e dependence yet. The ratios are expected to be reasonably insensitive to the variation of Z(eff). (C) 2007 American Institute of Physics.
Original languageEnglish
Pages (from-to)083301
Number of pages11
JournalPhysics of Plasmas
Volume14
Issue number8
DOIs
Publication statusPublished - 1 Aug 2007

Fingerprint

helium
metastable state
ion charge
fusion
electron energy
temperature dependence
ground state
temperature
sensitivity
profiles
predictions

Keywords

  • plasma density
  • metastable states
  • plasma collision processes
  • Tokamak devices
  • atomic beams

Cite this

Ahn, J-W., Craig, D., Fiksel, G., Den Hartog, D. J., Anderson, J. K., & O'Mullane, M. G. (2007). Emission intensities and line ratios from a fast neutral helium beam. Physics of Plasmas, 14(8), 083301. https://doi.org/10.1063/1.2759191
Ahn, J-W. ; Craig, D. ; Fiksel, G. ; Den Hartog, D.J. ; Anderson, J.K. ; O'Mullane, M.G. / Emission intensities and line ratios from a fast neutral helium beam. In: Physics of Plasmas. 2007 ; Vol. 14, No. 8. pp. 083301.
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Ahn, J-W, Craig, D, Fiksel, G, Den Hartog, DJ, Anderson, JK & O'Mullane, MG 2007, 'Emission intensities and line ratios from a fast neutral helium beam', Physics of Plasmas, vol. 14, no. 8, pp. 083301. https://doi.org/10.1063/1.2759191

Emission intensities and line ratios from a fast neutral helium beam. / Ahn, J-W.; Craig, D.; Fiksel, G.; Den Hartog, D.J.; Anderson, J.K.; O'Mullane, M.G.

In: Physics of Plasmas, Vol. 14, No. 8, 01.08.2007, p. 083301.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Emission intensities and line ratios from a fast neutral helium beam

AU - Ahn, J-W.

AU - Craig, D.

AU - Fiksel, G.

AU - Den Hartog, D.J.

AU - Anderson, J.K.

AU - O'Mullane, M.G.

PY - 2007/8/1

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N2 - The emission intensities and line ratios from a fast neutral helium beam is investigated in the Madison Symmetric Torus (MST) [R. N. Dexter, D. W. Kerst, T. W. Lovell, S. C. Prager, and J. C. Sprott, Fusion Technol. 19, 131 1991]. Predicted He I line intensities and line ratios from a recently developed collisional-radiative model are compared with experiment. The intensity of singlet lines comes mostly (>95 from the contribution of the ground state population and is very weakly dependent on the initial metastable fraction at the observation point in the plasma core. On the other hand, the intensity of triplet lines is strongly affected by the local metastable state (2(1)S and 2(3)S) populations and the initial metastable fraction plays an important role in determining line intensities. The fraction of local metastable states can only be estimated by making use of electron temperature (T-e), electron density (n(e)), and effective ion charge (Z(eff)) profiles as inputs to the population balance equations. This leads triplet lines to be unusable for the investigation of their local plasma parameter dependence. The ratio of singlet lines at 667.8 nm and 492.2 nm (I-667/I-492) as well as the ratio of 667.8 nm and 501.6 nm lines (I-667/I-501) has been investigated for the dependence on T-e and n(e) both theoretically and experimentally. I-667/I-492 shows strong dependence on n(e) with weak sensitivity to T-e. Measurements and predictions agree quantitatively within a factor of 2. There has been no ratio of singlet lines identified to have strong enough T-e dependence yet. The ratios are expected to be reasonably insensitive to the variation of Z(eff). (C) 2007 American Institute of Physics.

AB - The emission intensities and line ratios from a fast neutral helium beam is investigated in the Madison Symmetric Torus (MST) [R. N. Dexter, D. W. Kerst, T. W. Lovell, S. C. Prager, and J. C. Sprott, Fusion Technol. 19, 131 1991]. Predicted He I line intensities and line ratios from a recently developed collisional-radiative model are compared with experiment. The intensity of singlet lines comes mostly (>95 from the contribution of the ground state population and is very weakly dependent on the initial metastable fraction at the observation point in the plasma core. On the other hand, the intensity of triplet lines is strongly affected by the local metastable state (2(1)S and 2(3)S) populations and the initial metastable fraction plays an important role in determining line intensities. The fraction of local metastable states can only be estimated by making use of electron temperature (T-e), electron density (n(e)), and effective ion charge (Z(eff)) profiles as inputs to the population balance equations. This leads triplet lines to be unusable for the investigation of their local plasma parameter dependence. The ratio of singlet lines at 667.8 nm and 492.2 nm (I-667/I-492) as well as the ratio of 667.8 nm and 501.6 nm lines (I-667/I-501) has been investigated for the dependence on T-e and n(e) both theoretically and experimentally. I-667/I-492 shows strong dependence on n(e) with weak sensitivity to T-e. Measurements and predictions agree quantitatively within a factor of 2. There has been no ratio of singlet lines identified to have strong enough T-e dependence yet. The ratios are expected to be reasonably insensitive to the variation of Z(eff). (C) 2007 American Institute of Physics.

KW - plasma density

KW - metastable states

KW - plasma collision processes

KW - Tokamak devices

KW - atomic beams

U2 - 10.1063/1.2759191

DO - 10.1063/1.2759191

M3 - Article

VL - 14

SP - 083301

JO - Physics of Plasmas

JF - Physics of Plasmas

SN - 1070-664X

IS - 8

ER -