Survey of magnetohydrodynamic instabilities in the advanced stellarator Wendelstein 7-AS

A. Weller; M. Anton; J. Geiger; M. Hirsch; R. Jaenicke; A. Werner; C. Nührenberg; E. Sallander; D. A. Spong

doi:10.1063/1.1346633

Survey of magnetohydrodynamic instabilities in the advanced stellarator Wendelstein 7-AS

A. Weller, M. Anton, J. Geiger, M. Hirsch, R. Jaenicke, A. Werner, C. Nührenberg, E. Sallander, D. A. Spong

Plasma Theory and Modeling

Research output: Contribution to journal › Article › peer-review

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Abstract

Magnetohydrodynamic (MHD) instabilities in the Wendelstein 7-AS stellarator (W7-AS) [G. Grieger et al., Phys. Fluids B 4, 2081 (1992)] are characterized experimentally in various plasma parameter regimes and heating scenarios. The observations are compared with theoretical predictions for particular cases. In the high-β range (〈β〈≤2%) no clear evidence of a stability β-limit could be found yet. In the lower β regime fast panicle driven global Alfvén modes are the most important instabilities during neutral beam injection (NBI). Besides of coherent modes with almost no effect on the plasma performance additional Alfvén modes appear at higher frequencies up to 400 kHz, which show nonlinear phenomena-like bursting, frequency chirping, and MHD induced energy and fast particle losses. The activity of edge localized modes (ELMs) is investigated in NBI heated discharges. The issue of current driven instabilities and their potential stabilization by a stellarator field has been investigated with regard to the design of compact hybrid stellarator systems.

Original language	English
Pages (from-to)	931-956
Number of pages	26
Journal	Physics of Plasmas
Volume	8
Issue number	3
DOIs	https://doi.org/10.1063/1.1346633
State	Published - Mar 2001

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title = "Survey of magnetohydrodynamic instabilities in the advanced stellarator Wendelstein 7-AS",

abstract = "Magnetohydrodynamic (MHD) instabilities in the Wendelstein 7-AS stellarator (W7-AS) [G. Grieger et al., Phys. Fluids B 4, 2081 (1992)] are characterized experimentally in various plasma parameter regimes and heating scenarios. The observations are compared with theoretical predictions for particular cases. In the high-β range (〈β〈≤2%) no clear evidence of a stability β-limit could be found yet. In the lower β regime fast panicle driven global Alfv{\'e}n modes are the most important instabilities during neutral beam injection (NBI). Besides of coherent modes with almost no effect on the plasma performance additional Alfv{\'e}n modes appear at higher frequencies up to 400 kHz, which show nonlinear phenomena-like bursting, frequency chirping, and MHD induced energy and fast particle losses. The activity of edge localized modes (ELMs) is investigated in NBI heated discharges. The issue of current driven instabilities and their potential stabilization by a stellarator field has been investigated with regard to the design of compact hybrid stellarator systems.",

author = "A. Weller and M. Anton and J. Geiger and M. Hirsch and R. Jaenicke and A. Werner and C. N{\"u}hrenberg and E. Sallander and Spong, {D. A.}",

year = "2001",

month = mar,

doi = "10.1063/1.1346633",

language = "English",

volume = "8",

pages = "931--956",

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T1 - Survey of magnetohydrodynamic instabilities in the advanced stellarator Wendelstein 7-AS

AU - Weller, A.

AU - Anton, M.

AU - Geiger, J.

AU - Hirsch, M.

AU - Jaenicke, R.

AU - Werner, A.

AU - Nührenberg, C.

AU - Sallander, E.

AU - Spong, D. A.

PY - 2001/3

Y1 - 2001/3

N2 - Magnetohydrodynamic (MHD) instabilities in the Wendelstein 7-AS stellarator (W7-AS) [G. Grieger et al., Phys. Fluids B 4, 2081 (1992)] are characterized experimentally in various plasma parameter regimes and heating scenarios. The observations are compared with theoretical predictions for particular cases. In the high-β range (〈β〈≤2%) no clear evidence of a stability β-limit could be found yet. In the lower β regime fast panicle driven global Alfvén modes are the most important instabilities during neutral beam injection (NBI). Besides of coherent modes with almost no effect on the plasma performance additional Alfvén modes appear at higher frequencies up to 400 kHz, which show nonlinear phenomena-like bursting, frequency chirping, and MHD induced energy and fast particle losses. The activity of edge localized modes (ELMs) is investigated in NBI heated discharges. The issue of current driven instabilities and their potential stabilization by a stellarator field has been investigated with regard to the design of compact hybrid stellarator systems.

AB - Magnetohydrodynamic (MHD) instabilities in the Wendelstein 7-AS stellarator (W7-AS) [G. Grieger et al., Phys. Fluids B 4, 2081 (1992)] are characterized experimentally in various plasma parameter regimes and heating scenarios. The observations are compared with theoretical predictions for particular cases. In the high-β range (〈β〈≤2%) no clear evidence of a stability β-limit could be found yet. In the lower β regime fast panicle driven global Alfvén modes are the most important instabilities during neutral beam injection (NBI). Besides of coherent modes with almost no effect on the plasma performance additional Alfvén modes appear at higher frequencies up to 400 kHz, which show nonlinear phenomena-like bursting, frequency chirping, and MHD induced energy and fast particle losses. The activity of edge localized modes (ELMs) is investigated in NBI heated discharges. The issue of current driven instabilities and their potential stabilization by a stellarator field has been investigated with regard to the design of compact hybrid stellarator systems.

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JO - Physics of Plasmas

JF - Physics of Plasmas

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ER -

Survey of magnetohydrodynamic instabilities in the advanced stellarator Wendelstein 7-AS

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