Complex spectra in fusion plasmas

M.G. von Hellermann, G. Bertschinger, W. Biel, C. Giroud, R. Jaspers, C. Jupen, O. Marchuk, M. O'Mullane, H.P. Summers, A. Whiteford, K.D. Zastrow

Research output: Contribution to journalArticle

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Abstract

The need for quantitative evaluation of complex line emission spectra as observed in hot fusion plasmas initiated a challenging development of sophisticated interpretation tools based on integrating advanced atomic modelling with detailed treatment of the plasma environment. The successful merging of the two worlds has led to routine diagnostic procedures which have contributed enormously to the understanding of underlying plasma processes and also to a wide acceptance of spectroscopy as a reliable diagnostic method. In this paper three characteristic types of spectra of current and continuing interest are presented. The first is that of medium/heavy species with many ionisation stages revealed in survey VUV and XUV spectra. Such species occur as control gases, as wall materials, as ablated heavy species and possible as layered wall dopants for monitoring erosion. The spectra are complex with line-like and quasi-continuum regions and are amenable to advanced 'pattern recognition' methods. The second type is of few electron, highly ionised systems observed as line-of-sight integrated passive emission spectra in the soft x-ray region. They are analysed successfully in terms of plasma parameters through matching of observation with predicted synthetic spectra. Examples used here include highly resolved helium-like emission spectra of argon, iron and titanium observed on the tokamaks TEXTOR and Tore Supra. The third type, and the emphasis of this work, comprises spectra linked to active beam spectroscopy, that is, charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES). In this case, a complex spectrum is again composed of a (usually) dominating active spectrum and an underlying passive emission spectrum. Its analysis requires modelling of both active and passive features. Examples used here are from the CXRS diagnostic at JET and TEXTOR. They display characteristic features of the main light impurity ions (C+6, He+2, N+7, Ne+10 and Ar+18), as well as that of the bulk plasma ions, H+, D+ and T+. A main conclusion is that spectral complexity is not necessarily negative, but that 'complex structures' can provide a rich source of information on the plasma and its parameters - provided it is matched with integrated analysis - and that the methods can have universal applicability. In the present preparatory phase of the next generation fusion experiment ITER (International Thermonuclear Experimental Reactor) the concepts and expectations of complex spectra and integrated data analysis play an important role in the design and optimisation procedure of the ITER diagnostic assembly.
LanguageEnglish
Pages19-29
Number of pages10
JournalPhysica Scripta
VolumeT120
DOIs
Publication statusPublished - 2005

Fingerprint

Fusion
Plasma
fusion
emission spectra
Spectroscopy
spectroscopy
Diagnostics
charge exchange
reactors
Recombination
Reactor
Line
Charge
pattern recognition
acceptability
line of sight
erosion
line spectra
ions
Soft X-ray

Keywords

  • x-ray spectroscopy
  • exchange recombination spectroscopy
  • neutral-beam injection
  • ion temperature
  • jet
  • emission
  • tokamak
  • diagnostics
  • deduction
  • densities
  • plasma

Cite this

von Hellermann, M. G., Bertschinger, G., Biel, W., Giroud, C., Jaspers, R., Jupen, C., ... Zastrow, K. D. (2005). Complex spectra in fusion plasmas. Physica Scripta, T120, 19-29. https://doi.org/10.1088/0031-8949/2005/T120/003
von Hellermann, M.G. ; Bertschinger, G. ; Biel, W. ; Giroud, C. ; Jaspers, R. ; Jupen, C. ; Marchuk, O. ; O'Mullane, M. ; Summers, H.P. ; Whiteford, A. ; Zastrow, K.D. / Complex spectra in fusion plasmas. In: Physica Scripta. 2005 ; Vol. T120. pp. 19-29.
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von Hellermann, MG, Bertschinger, G, Biel, W, Giroud, C, Jaspers, R, Jupen, C, Marchuk, O, O'Mullane, M, Summers, HP, Whiteford, A & Zastrow, KD 2005, 'Complex spectra in fusion plasmas' Physica Scripta, vol. T120, pp. 19-29. https://doi.org/10.1088/0031-8949/2005/T120/003

Complex spectra in fusion plasmas. / von Hellermann, M.G.; Bertschinger, G.; Biel, W.; Giroud, C.; Jaspers, R.; Jupen, C.; Marchuk, O.; O'Mullane, M.; Summers, H.P.; Whiteford, A.; Zastrow, K.D.

In: Physica Scripta, Vol. T120, 2005, p. 19-29.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Complex spectra in fusion plasmas

AU - von Hellermann, M.G.

AU - Bertschinger, G.

AU - Biel, W.

AU - Giroud, C.

AU - Jaspers, R.

AU - Jupen, C.

AU - Marchuk, O.

AU - O'Mullane, M.

AU - Summers, H.P.

AU - Whiteford, A.

AU - Zastrow, K.D.

PY - 2005

Y1 - 2005

N2 - The need for quantitative evaluation of complex line emission spectra as observed in hot fusion plasmas initiated a challenging development of sophisticated interpretation tools based on integrating advanced atomic modelling with detailed treatment of the plasma environment. The successful merging of the two worlds has led to routine diagnostic procedures which have contributed enormously to the understanding of underlying plasma processes and also to a wide acceptance of spectroscopy as a reliable diagnostic method. In this paper three characteristic types of spectra of current and continuing interest are presented. The first is that of medium/heavy species with many ionisation stages revealed in survey VUV and XUV spectra. Such species occur as control gases, as wall materials, as ablated heavy species and possible as layered wall dopants for monitoring erosion. The spectra are complex with line-like and quasi-continuum regions and are amenable to advanced 'pattern recognition' methods. The second type is of few electron, highly ionised systems observed as line-of-sight integrated passive emission spectra in the soft x-ray region. They are analysed successfully in terms of plasma parameters through matching of observation with predicted synthetic spectra. Examples used here include highly resolved helium-like emission spectra of argon, iron and titanium observed on the tokamaks TEXTOR and Tore Supra. The third type, and the emphasis of this work, comprises spectra linked to active beam spectroscopy, that is, charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES). In this case, a complex spectrum is again composed of a (usually) dominating active spectrum and an underlying passive emission spectrum. Its analysis requires modelling of both active and passive features. Examples used here are from the CXRS diagnostic at JET and TEXTOR. They display characteristic features of the main light impurity ions (C+6, He+2, N+7, Ne+10 and Ar+18), as well as that of the bulk plasma ions, H+, D+ and T+. A main conclusion is that spectral complexity is not necessarily negative, but that 'complex structures' can provide a rich source of information on the plasma and its parameters - provided it is matched with integrated analysis - and that the methods can have universal applicability. In the present preparatory phase of the next generation fusion experiment ITER (International Thermonuclear Experimental Reactor) the concepts and expectations of complex spectra and integrated data analysis play an important role in the design and optimisation procedure of the ITER diagnostic assembly.

AB - The need for quantitative evaluation of complex line emission spectra as observed in hot fusion plasmas initiated a challenging development of sophisticated interpretation tools based on integrating advanced atomic modelling with detailed treatment of the plasma environment. The successful merging of the two worlds has led to routine diagnostic procedures which have contributed enormously to the understanding of underlying plasma processes and also to a wide acceptance of spectroscopy as a reliable diagnostic method. In this paper three characteristic types of spectra of current and continuing interest are presented. The first is that of medium/heavy species with many ionisation stages revealed in survey VUV and XUV spectra. Such species occur as control gases, as wall materials, as ablated heavy species and possible as layered wall dopants for monitoring erosion. The spectra are complex with line-like and quasi-continuum regions and are amenable to advanced 'pattern recognition' methods. The second type is of few electron, highly ionised systems observed as line-of-sight integrated passive emission spectra in the soft x-ray region. They are analysed successfully in terms of plasma parameters through matching of observation with predicted synthetic spectra. Examples used here include highly resolved helium-like emission spectra of argon, iron and titanium observed on the tokamaks TEXTOR and Tore Supra. The third type, and the emphasis of this work, comprises spectra linked to active beam spectroscopy, that is, charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES). In this case, a complex spectrum is again composed of a (usually) dominating active spectrum and an underlying passive emission spectrum. Its analysis requires modelling of both active and passive features. Examples used here are from the CXRS diagnostic at JET and TEXTOR. They display characteristic features of the main light impurity ions (C+6, He+2, N+7, Ne+10 and Ar+18), as well as that of the bulk plasma ions, H+, D+ and T+. A main conclusion is that spectral complexity is not necessarily negative, but that 'complex structures' can provide a rich source of information on the plasma and its parameters - provided it is matched with integrated analysis - and that the methods can have universal applicability. In the present preparatory phase of the next generation fusion experiment ITER (International Thermonuclear Experimental Reactor) the concepts and expectations of complex spectra and integrated data analysis play an important role in the design and optimisation procedure of the ITER diagnostic assembly.

KW - x-ray spectroscopy

KW - exchange recombination spectroscopy

KW - neutral-beam injection

KW - ion temperature

KW - jet

KW - emission

KW - tokamak

KW - diagnostics

KW - deduction

KW - densities

KW - plasma

UR - http://dx.doi.org/10.1088/0031-8949/2005/T120/003

U2 - 10.1088/0031-8949/2005/T120/003

DO - 10.1088/0031-8949/2005/T120/003

M3 - Article

VL - T120

SP - 19

EP - 29

JO - Physica Scripta

T2 - Physica Scripta

JF - Physica Scripta

SN - 0031-8949

ER -

von Hellermann MG, Bertschinger G, Biel W, Giroud C, Jaspers R, Jupen C et al. Complex spectra in fusion plasmas. Physica Scripta. 2005;T120:19-29. https://doi.org/10.1088/0031-8949/2005/T120/003