A current-driven electromagnetic mode in sheared and toroidal configurations

István Pusztai; Peter J. Catto; Felix I. Parra; Michael Barnes

doi:10.1088/0741-3335/56/3/035011

A current-driven electromagnetic mode in sheared and toroidal configurations

István Pusztai, Peter J. Catto, Felix I. Parra, Michael Barnes

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

3 Scopus citations

Abstract

The induced electric field in a tokamak drives a parallel electron current flow. In an inhomogeneous, finite beta plasma, when this electron flow is comparable to the ion thermal speed, the Alfvén mode wave solutions of the electromagnetic gyrokinetic equation can become nearly purely growing kink modes. Using the new 'low-flow' version of the gyrokinetic code GS2 developed for momentum transport studies (Barnes et al 2013 Phys. Rev. Lett. 111 055005), we are able to model the effect of the induced parallel electric field on the electron distribution to study the destabilizing influence of current on stability. We identify high mode number kink modes in GS2 simulations and make comparisons to analytical theory in sheared magnetic geometry. We demonstrate reassuring agreement with analytical results both in terms of parametric dependences of mode frequencies and growth rates, and regarding the radial mode structure.

Original language	English (US)
Article number	035011
Journal	Plasma Physics and Controlled Fusion
Volume	56
Issue number	3
DOIs	https://doi.org/10.1088/0741-3335/56/3/035011
State	Published - Mar 2014
Externally published	Yes

All Science Journal Classification (ASJC) codes

Nuclear Energy and Engineering
Condensed Matter Physics

Keywords

current gradient
gyrokinetic
instability
kink mode
simulation

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10.1088/0741-3335/56/3/035011

Cite this

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title = "A current-driven electromagnetic mode in sheared and toroidal configurations",

abstract = "The induced electric field in a tokamak drives a parallel electron current flow. In an inhomogeneous, finite beta plasma, when this electron flow is comparable to the ion thermal speed, the Alfv{\'e}n mode wave solutions of the electromagnetic gyrokinetic equation can become nearly purely growing kink modes. Using the new 'low-flow' version of the gyrokinetic code GS2 developed for momentum transport studies (Barnes et al 2013 Phys. Rev. Lett. 111 055005), we are able to model the effect of the induced parallel electric field on the electron distribution to study the destabilizing influence of current on stability. We identify high mode number kink modes in GS2 simulations and make comparisons to analytical theory in sheared magnetic geometry. We demonstrate reassuring agreement with analytical results both in terms of parametric dependences of mode frequencies and growth rates, and regarding the radial mode structure.",

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author = "Istv{\'a}n Pusztai and Catto, {Peter J.} and Parra, {Felix I.} and Michael Barnes",

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T1 - A current-driven electromagnetic mode in sheared and toroidal configurations

AU - Pusztai, István

AU - Catto, Peter J.

AU - Parra, Felix I.

AU - Barnes, Michael

PY - 2014/3

Y1 - 2014/3

N2 - The induced electric field in a tokamak drives a parallel electron current flow. In an inhomogeneous, finite beta plasma, when this electron flow is comparable to the ion thermal speed, the Alfvén mode wave solutions of the electromagnetic gyrokinetic equation can become nearly purely growing kink modes. Using the new 'low-flow' version of the gyrokinetic code GS2 developed for momentum transport studies (Barnes et al 2013 Phys. Rev. Lett. 111 055005), we are able to model the effect of the induced parallel electric field on the electron distribution to study the destabilizing influence of current on stability. We identify high mode number kink modes in GS2 simulations and make comparisons to analytical theory in sheared magnetic geometry. We demonstrate reassuring agreement with analytical results both in terms of parametric dependences of mode frequencies and growth rates, and regarding the radial mode structure.

AB - The induced electric field in a tokamak drives a parallel electron current flow. In an inhomogeneous, finite beta plasma, when this electron flow is comparable to the ion thermal speed, the Alfvén mode wave solutions of the electromagnetic gyrokinetic equation can become nearly purely growing kink modes. Using the new 'low-flow' version of the gyrokinetic code GS2 developed for momentum transport studies (Barnes et al 2013 Phys. Rev. Lett. 111 055005), we are able to model the effect of the induced parallel electric field on the electron distribution to study the destabilizing influence of current on stability. We identify high mode number kink modes in GS2 simulations and make comparisons to analytical theory in sheared magnetic geometry. We demonstrate reassuring agreement with analytical results both in terms of parametric dependences of mode frequencies and growth rates, and regarding the radial mode structure.

KW - current gradient

KW - gyrokinetic

KW - instability

KW - kink mode

KW - simulation

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A current-driven electromagnetic mode in sheared and toroidal configurations

Abstract

All Science Journal Classification (ASJC) codes

Keywords

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