Experimental investigation of the radial structure of energetic particle driven modes

L. Horváth, G. Papp, Ph Lauber, G. Por, A. Gude, V. Igochine, B. Geiger, M. Maraschek, L. Guimarais, V. Nikolaeva, G. I. Pokol

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Alfvén eigenmodes (AEs) and energetic particle modes (EPMs) are often excited by energetic particles (EPs) in tokamak plasmas. One of the main open questions concerning EP driven instabilities is the non-linear evolution of the mode structure. The aim of the present paper is to investigate the properties of beta-induced AEs (BAEs) and EP driven geodesic acoustic modes (EGAMs) observed in the ramp-up phase of off-axis NBI heated ASDEX Upgrade (AUG) discharges. This paper focuses on the changes in the mode structure of BAEs/EGAMs during the non-linear chirping phase. Our investigation has shown that in the case of the observed down-chirping BAEs the changes in the radial structure are smaller than the uncertainty of our measurement. This behaviour is most probably the consequence of the fact that BAEs are normal modes, thus their radial structure strongly depends on the background plasma parameters rather than on the EP distribution. In the case of rapidly upward chirping EGAMs the analysis consistently shows shrinkage of the mode structure. The proposed explanation is that the resonance in the velocity space moves towards more passing particles which have narrower orbit widths.

Original languageEnglish
Article number112003
JournalNuclear Fusion
Volume56
Issue number11
DOIs
Publication statusPublished - Jul 22 2016

Fingerprint

energetic particles
acoustics
ramps
shrinkage
orbits

Keywords

  • Alfven eigenmodes
  • energetic ions
  • time-frequency analysis
  • tokamak
  • wave-particle interaction

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Horváth, L., Papp, G., Lauber, P., Por, G., Gude, A., Igochine, V., ... Pokol, G. I. (2016). Experimental investigation of the radial structure of energetic particle driven modes. Nuclear Fusion, 56(11), [112003]. https://doi.org/10.1088/0029-5515/56/11/112003

Experimental investigation of the radial structure of energetic particle driven modes. / Horváth, L.; Papp, G.; Lauber, Ph; Por, G.; Gude, A.; Igochine, V.; Geiger, B.; Maraschek, M.; Guimarais, L.; Nikolaeva, V.; Pokol, G. I.

In: Nuclear Fusion, Vol. 56, No. 11, 112003, 22.07.2016.

Research output: Contribution to journalArticle

Horváth, L, Papp, G, Lauber, P, Por, G, Gude, A, Igochine, V, Geiger, B, Maraschek, M, Guimarais, L, Nikolaeva, V & Pokol, GI 2016, 'Experimental investigation of the radial structure of energetic particle driven modes', Nuclear Fusion, vol. 56, no. 11, 112003. https://doi.org/10.1088/0029-5515/56/11/112003
Horváth, L. ; Papp, G. ; Lauber, Ph ; Por, G. ; Gude, A. ; Igochine, V. ; Geiger, B. ; Maraschek, M. ; Guimarais, L. ; Nikolaeva, V. ; Pokol, G. I. / Experimental investigation of the radial structure of energetic particle driven modes. In: Nuclear Fusion. 2016 ; Vol. 56, No. 11.
@article{4074d5b7be624329ba8595e6b9ebaf34,
title = "Experimental investigation of the radial structure of energetic particle driven modes",
abstract = "Alfv{\'e}n eigenmodes (AEs) and energetic particle modes (EPMs) are often excited by energetic particles (EPs) in tokamak plasmas. One of the main open questions concerning EP driven instabilities is the non-linear evolution of the mode structure. The aim of the present paper is to investigate the properties of beta-induced AEs (BAEs) and EP driven geodesic acoustic modes (EGAMs) observed in the ramp-up phase of off-axis NBI heated ASDEX Upgrade (AUG) discharges. This paper focuses on the changes in the mode structure of BAEs/EGAMs during the non-linear chirping phase. Our investigation has shown that in the case of the observed down-chirping BAEs the changes in the radial structure are smaller than the uncertainty of our measurement. This behaviour is most probably the consequence of the fact that BAEs are normal modes, thus their radial structure strongly depends on the background plasma parameters rather than on the EP distribution. In the case of rapidly upward chirping EGAMs the analysis consistently shows shrinkage of the mode structure. The proposed explanation is that the resonance in the velocity space moves towards more passing particles which have narrower orbit widths.",
keywords = "Alfven eigenmodes, energetic ions, time-frequency analysis, tokamak, wave-particle interaction",
author = "L. Horv{\'a}th and G. Papp and Ph Lauber and G. Por and A. Gude and V. Igochine and B. Geiger and M. Maraschek and L. Guimarais and V. Nikolaeva and Pokol, {G. I.}",
year = "2016",
month = "7",
day = "22",
doi = "10.1088/0029-5515/56/11/112003",
language = "English",
volume = "56",
journal = "Nuclear Fusion",
issn = "0029-5515",
publisher = "IOP Publishing Ltd.",
number = "11",

}

TY - JOUR

T1 - Experimental investigation of the radial structure of energetic particle driven modes

AU - Horváth, L.

AU - Papp, G.

AU - Lauber, Ph

AU - Por, G.

AU - Gude, A.

AU - Igochine, V.

AU - Geiger, B.

AU - Maraschek, M.

AU - Guimarais, L.

AU - Nikolaeva, V.

AU - Pokol, G. I.

PY - 2016/7/22

Y1 - 2016/7/22

N2 - Alfvén eigenmodes (AEs) and energetic particle modes (EPMs) are often excited by energetic particles (EPs) in tokamak plasmas. One of the main open questions concerning EP driven instabilities is the non-linear evolution of the mode structure. The aim of the present paper is to investigate the properties of beta-induced AEs (BAEs) and EP driven geodesic acoustic modes (EGAMs) observed in the ramp-up phase of off-axis NBI heated ASDEX Upgrade (AUG) discharges. This paper focuses on the changes in the mode structure of BAEs/EGAMs during the non-linear chirping phase. Our investigation has shown that in the case of the observed down-chirping BAEs the changes in the radial structure are smaller than the uncertainty of our measurement. This behaviour is most probably the consequence of the fact that BAEs are normal modes, thus their radial structure strongly depends on the background plasma parameters rather than on the EP distribution. In the case of rapidly upward chirping EGAMs the analysis consistently shows shrinkage of the mode structure. The proposed explanation is that the resonance in the velocity space moves towards more passing particles which have narrower orbit widths.

AB - Alfvén eigenmodes (AEs) and energetic particle modes (EPMs) are often excited by energetic particles (EPs) in tokamak plasmas. One of the main open questions concerning EP driven instabilities is the non-linear evolution of the mode structure. The aim of the present paper is to investigate the properties of beta-induced AEs (BAEs) and EP driven geodesic acoustic modes (EGAMs) observed in the ramp-up phase of off-axis NBI heated ASDEX Upgrade (AUG) discharges. This paper focuses on the changes in the mode structure of BAEs/EGAMs during the non-linear chirping phase. Our investigation has shown that in the case of the observed down-chirping BAEs the changes in the radial structure are smaller than the uncertainty of our measurement. This behaviour is most probably the consequence of the fact that BAEs are normal modes, thus their radial structure strongly depends on the background plasma parameters rather than on the EP distribution. In the case of rapidly upward chirping EGAMs the analysis consistently shows shrinkage of the mode structure. The proposed explanation is that the resonance in the velocity space moves towards more passing particles which have narrower orbit widths.

KW - Alfven eigenmodes

KW - energetic ions

KW - time-frequency analysis

KW - tokamak

KW - wave-particle interaction

UR - http://www.scopus.com/inward/record.url?scp=84993967079&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84993967079&partnerID=8YFLogxK

U2 - 10.1088/0029-5515/56/11/112003

DO - 10.1088/0029-5515/56/11/112003

M3 - Article

AN - SCOPUS:84993967079

VL - 56

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 11

M1 - 112003

ER -