Time-resonant tokamak plasma edge instabilities?

A.J. Webster (Corresponding Author), R.O. Dendy, F.A. Calderon, S.C. Chapman, E. Delabie, D. Dodt, R. Felton, T.N. Todd, F. Maviglia, J. Morris, V. Riccardo, B. Alper, S. Brezinsek, P. Coad, Jari Likonen, M. Rubel, JET EFDA Contributors

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)

Abstract

For a two week period during the Joint European Torus 2012 experimental campaign, the same high confinement plasma was repeated 151 times. The dataset was analysed to produce a probability density function (pdf) for the waiting times between edge-localized plasma instabilities (ELMs). The result was entirely unexpected. Instead of a smooth single peaked pdf, a succession of 4-5 sharp maxima and minima uniformly separated by 7-8ms intervals was found. Here we explore the causes of this newly observed phenomenon, and conclude that it is either due to a naturally occurring self-organized plasma phenomenon or an interaction between the plasma and a real-time control system. If the maxima are a result of 'resonant' frequencies at which ELMs can be triggered more easily, then future ELM control techniques can, and probably will, use them. Either way, these results demand a deeper understanding of the ELM process.
Original languageEnglish
Number of pages6
JournalPlasma Physics and Controlled Fusion
Volume56
Issue number7
DOIs
Publication statusPublished - 2014
MoE publication typeA1 Journal article-refereed

Fingerprint

Plasma stability
probability density functions
Probability density function
Joint European Torus
Plasmas
Plasma confinement
plasma control
magnetohydrodynamic stability
Real time control
Beam plasma interactions
resonant frequencies
Natural frequencies
intervals
Control systems
causes
interactions

Keywords

  • plasma physics
  • tokamaks
  • microinstabilities

Cite this

Webster, A. J., Dendy, R. O., Calderon, F. A., Chapman, S. C., Delabie, E., Dodt, D., ... Contributors, JET. EFDA. (2014). Time-resonant tokamak plasma edge instabilities? Plasma Physics and Controlled Fusion, 56(7). https://doi.org/10.1088/0741-3335/56/7/075017
Webster, A.J. ; Dendy, R.O. ; Calderon, F.A. ; Chapman, S.C. ; Delabie, E. ; Dodt, D. ; Felton, R. ; Todd, T.N. ; Maviglia, F. ; Morris, J. ; Riccardo, V. ; Alper, B. ; Brezinsek, S. ; Coad, P. ; Likonen, Jari ; Rubel, M. ; Contributors, JET EFDA. / Time-resonant tokamak plasma edge instabilities?. In: Plasma Physics and Controlled Fusion. 2014 ; Vol. 56, No. 7.
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title = "Time-resonant tokamak plasma edge instabilities?",
abstract = "For a two week period during the Joint European Torus 2012 experimental campaign, the same high confinement plasma was repeated 151 times. The dataset was analysed to produce a probability density function (pdf) for the waiting times between edge-localized plasma instabilities (ELMs). The result was entirely unexpected. Instead of a smooth single peaked pdf, a succession of 4-5 sharp maxima and minima uniformly separated by 7-8ms intervals was found. Here we explore the causes of this newly observed phenomenon, and conclude that it is either due to a naturally occurring self-organized plasma phenomenon or an interaction between the plasma and a real-time control system. If the maxima are a result of 'resonant' frequencies at which ELMs can be triggered more easily, then future ELM control techniques can, and probably will, use them. Either way, these results demand a deeper understanding of the ELM process.",
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Webster, AJ, Dendy, RO, Calderon, FA, Chapman, SC, Delabie, E, Dodt, D, Felton, R, Todd, TN, Maviglia, F, Morris, J, Riccardo, V, Alper, B, Brezinsek, S, Coad, P, Likonen, J, Rubel, M & Contributors, JETEFDA 2014, 'Time-resonant tokamak plasma edge instabilities?', Plasma Physics and Controlled Fusion, vol. 56, no. 7. https://doi.org/10.1088/0741-3335/56/7/075017

Time-resonant tokamak plasma edge instabilities? / Webster, A.J. (Corresponding Author); Dendy, R.O.; Calderon, F.A.; Chapman, S.C.; Delabie, E.; Dodt, D.; Felton, R.; Todd, T.N.; Maviglia, F.; Morris, J.; Riccardo, V.; Alper, B.; Brezinsek, S.; Coad, P.; Likonen, Jari; Rubel, M.; Contributors, JET EFDA.

In: Plasma Physics and Controlled Fusion, Vol. 56, No. 7, 2014.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Time-resonant tokamak plasma edge instabilities?

AU - Webster, A.J.

AU - Dendy, R.O.

AU - Calderon, F.A.

AU - Chapman, S.C.

AU - Delabie, E.

AU - Dodt, D.

AU - Felton, R.

AU - Todd, T.N.

AU - Maviglia, F.

AU - Morris, J.

AU - Riccardo, V.

AU - Alper, B.

AU - Brezinsek, S.

AU - Coad, P.

AU - Likonen, Jari

AU - Rubel, M.

AU - Contributors, JET EFDA

PY - 2014

Y1 - 2014

N2 - For a two week period during the Joint European Torus 2012 experimental campaign, the same high confinement plasma was repeated 151 times. The dataset was analysed to produce a probability density function (pdf) for the waiting times between edge-localized plasma instabilities (ELMs). The result was entirely unexpected. Instead of a smooth single peaked pdf, a succession of 4-5 sharp maxima and minima uniformly separated by 7-8ms intervals was found. Here we explore the causes of this newly observed phenomenon, and conclude that it is either due to a naturally occurring self-organized plasma phenomenon or an interaction between the plasma and a real-time control system. If the maxima are a result of 'resonant' frequencies at which ELMs can be triggered more easily, then future ELM control techniques can, and probably will, use them. Either way, these results demand a deeper understanding of the ELM process.

AB - For a two week period during the Joint European Torus 2012 experimental campaign, the same high confinement plasma was repeated 151 times. The dataset was analysed to produce a probability density function (pdf) for the waiting times between edge-localized plasma instabilities (ELMs). The result was entirely unexpected. Instead of a smooth single peaked pdf, a succession of 4-5 sharp maxima and minima uniformly separated by 7-8ms intervals was found. Here we explore the causes of this newly observed phenomenon, and conclude that it is either due to a naturally occurring self-organized plasma phenomenon or an interaction between the plasma and a real-time control system. If the maxima are a result of 'resonant' frequencies at which ELMs can be triggered more easily, then future ELM control techniques can, and probably will, use them. Either way, these results demand a deeper understanding of the ELM process.

KW - plasma physics

KW - tokamaks

KW - microinstabilities

U2 - 10.1088/0741-3335/56/7/075017

DO - 10.1088/0741-3335/56/7/075017

M3 - Article

VL - 56

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

SN - 0741-3335

IS - 7

ER -

Webster AJ, Dendy RO, Calderon FA, Chapman SC, Delabie E, Dodt D et al. Time-resonant tokamak plasma edge instabilities? Plasma Physics and Controlled Fusion. 2014;56(7). https://doi.org/10.1088/0741-3335/56/7/075017