The role of temperature fluctuations in the dynamics of type-I and type-II edge localized modes at ASDEX Upgrade

I.G.J. Classen, J.E. Boom, A. Bogomolov, E. Wolfrum, M. Maraschek, W. Suttrop, P.C. de Vries, A.J.H. Donné, B.J. Tobias, C.W. Domier, N.C. Luhmann

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Abstract

Two-dimensional temperature measurements using the electron cyclotron emission imaging diagnostic at ASDEX Upgrade revealed a variety of temperature fluctuations associated with type-I and type-II edge localized modes (ELMs). The characteristics and dynamics of these modes, and their role in the ELM cycle, are presented. During type-I ELMs, different phases of distinct mode activity have been identified. At the onset of the ELM crash, a short lived mode is observed in the pedestal region. During the actual crash phase, multiple filamentary structures are observed just outside the separatrix. A third type of fluctuation, the inter-ELM mode, is often observed in between type-I crashes. The occurrence of this mode tends to lengthen the ELM period. During type-I ELM suppression with magnetic perturbation coils, smaller crash events become more frequent, replacing the large type-I crashes. In type-II ELMs, temperature crashes are absent altogether, and a continuous broadband fluctuation in the 20–60 kHz range, showing beat wave like behaviour, is observed. The similarities between the characteristics of this mode and the inter-ELM mode suggest that it is the same instability. In type-I ELMs it delays the next crash, in type-II ELMs it might be responsible for the complete absence of crash events.
Original languageEnglish
Article number073005
Pages (from-to)073005
Number of pages7
JournalNuclear Fusion
Volume53
Issue number7
DOIs
Publication statusPublished - 2013

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crashes
temperature
cyclotrons
temperature measurement
synchronism
coils
retarding
occurrences
broadband
perturbation
cycles

Cite this

Classen, I. G. J., Boom, J. E., Bogomolov, A., Wolfrum, E., Maraschek, M., Suttrop, W., ... Luhmann, N. C. (2013). The role of temperature fluctuations in the dynamics of type-I and type-II edge localized modes at ASDEX Upgrade. Nuclear Fusion, 53(7), 073005. [073005]. https://doi.org/10.1088/0029-5515/53/7/073005
Classen, I.G.J. ; Boom, J.E. ; Bogomolov, A. ; Wolfrum, E. ; Maraschek, M. ; Suttrop, W. ; de Vries, P.C. ; Donné, A.J.H. ; Tobias, B.J. ; Domier, C.W. ; Luhmann, N.C. / The role of temperature fluctuations in the dynamics of type-I and type-II edge localized modes at ASDEX Upgrade. In: Nuclear Fusion. 2013 ; Vol. 53, No. 7. pp. 073005.
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abstract = "Two-dimensional temperature measurements using the electron cyclotron emission imaging diagnostic at ASDEX Upgrade revealed a variety of temperature fluctuations associated with type-I and type-II edge localized modes (ELMs). The characteristics and dynamics of these modes, and their role in the ELM cycle, are presented. During type-I ELMs, different phases of distinct mode activity have been identified. At the onset of the ELM crash, a short lived mode is observed in the pedestal region. During the actual crash phase, multiple filamentary structures are observed just outside the separatrix. A third type of fluctuation, the inter-ELM mode, is often observed in between type-I crashes. The occurrence of this mode tends to lengthen the ELM period. During type-I ELM suppression with magnetic perturbation coils, smaller crash events become more frequent, replacing the large type-I crashes. In type-II ELMs, temperature crashes are absent altogether, and a continuous broadband fluctuation in the 20–60 kHz range, showing beat wave like behaviour, is observed. The similarities between the characteristics of this mode and the inter-ELM mode suggest that it is the same instability. In type-I ELMs it delays the next crash, in type-II ELMs it might be responsible for the complete absence of crash events.",
author = "I.G.J. Classen and J.E. Boom and A. Bogomolov and E. Wolfrum and M. Maraschek and W. Suttrop and {de Vries}, P.C. and A.J.H. Donn{\'e} and B.J. Tobias and C.W. Domier and N.C. Luhmann",
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Classen, IGJ, Boom, JE, Bogomolov, A, Wolfrum, E, Maraschek, M, Suttrop, W, de Vries, PC, Donné, AJH, Tobias, BJ, Domier, CW & Luhmann, NC 2013, 'The role of temperature fluctuations in the dynamics of type-I and type-II edge localized modes at ASDEX Upgrade', Nuclear Fusion, vol. 53, no. 7, 073005, pp. 073005. https://doi.org/10.1088/0029-5515/53/7/073005

The role of temperature fluctuations in the dynamics of type-I and type-II edge localized modes at ASDEX Upgrade. / Classen, I.G.J.; Boom, J.E.; Bogomolov, A.; Wolfrum, E.; Maraschek, M.; Suttrop, W.; de Vries, P.C.; Donné, A.J.H.; Tobias, B.J.; Domier, C.W.; Luhmann, N.C.

In: Nuclear Fusion, Vol. 53, No. 7, 073005, 2013, p. 073005.

Research output: Contribution to journalArticleAcademicpeer-review

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T1 - The role of temperature fluctuations in the dynamics of type-I and type-II edge localized modes at ASDEX Upgrade

AU - Classen, I.G.J.

AU - Boom, J.E.

AU - Bogomolov, A.

AU - Wolfrum, E.

AU - Maraschek, M.

AU - Suttrop, W.

AU - de Vries, P.C.

AU - Donné, A.J.H.

AU - Tobias, B.J.

AU - Domier, C.W.

AU - Luhmann, N.C.

PY - 2013

Y1 - 2013

N2 - Two-dimensional temperature measurements using the electron cyclotron emission imaging diagnostic at ASDEX Upgrade revealed a variety of temperature fluctuations associated with type-I and type-II edge localized modes (ELMs). The characteristics and dynamics of these modes, and their role in the ELM cycle, are presented. During type-I ELMs, different phases of distinct mode activity have been identified. At the onset of the ELM crash, a short lived mode is observed in the pedestal region. During the actual crash phase, multiple filamentary structures are observed just outside the separatrix. A third type of fluctuation, the inter-ELM mode, is often observed in between type-I crashes. The occurrence of this mode tends to lengthen the ELM period. During type-I ELM suppression with magnetic perturbation coils, smaller crash events become more frequent, replacing the large type-I crashes. In type-II ELMs, temperature crashes are absent altogether, and a continuous broadband fluctuation in the 20–60 kHz range, showing beat wave like behaviour, is observed. The similarities between the characteristics of this mode and the inter-ELM mode suggest that it is the same instability. In type-I ELMs it delays the next crash, in type-II ELMs it might be responsible for the complete absence of crash events.

AB - Two-dimensional temperature measurements using the electron cyclotron emission imaging diagnostic at ASDEX Upgrade revealed a variety of temperature fluctuations associated with type-I and type-II edge localized modes (ELMs). The characteristics and dynamics of these modes, and their role in the ELM cycle, are presented. During type-I ELMs, different phases of distinct mode activity have been identified. At the onset of the ELM crash, a short lived mode is observed in the pedestal region. During the actual crash phase, multiple filamentary structures are observed just outside the separatrix. A third type of fluctuation, the inter-ELM mode, is often observed in between type-I crashes. The occurrence of this mode tends to lengthen the ELM period. During type-I ELM suppression with magnetic perturbation coils, smaller crash events become more frequent, replacing the large type-I crashes. In type-II ELMs, temperature crashes are absent altogether, and a continuous broadband fluctuation in the 20–60 kHz range, showing beat wave like behaviour, is observed. The similarities between the characteristics of this mode and the inter-ELM mode suggest that it is the same instability. In type-I ELMs it delays the next crash, in type-II ELMs it might be responsible for the complete absence of crash events.

U2 - 10.1088/0029-5515/53/7/073005

DO - 10.1088/0029-5515/53/7/073005

M3 - Article

VL - 53

SP - 073005

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 7

M1 - 073005

ER -