A current-driven electromagnetic mode in sheared and toroidal configurations
Journal article, 2014

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 Alfven 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.


kink mode



current gradient


Istvan Pusztai

Chalmers, Applied Physics, Nuclear Engineering

P. J. Catto

Massachusetts Institute of Technology (MIT)

F. I. Parra

University of Oxford

Massachusetts Institute of Technology (MIT)

M. Barnes

Massachusetts Institute of Technology (MIT)

The University of Texas at Austin

Plasma Physics and Controlled Fusion

0741-3335 (ISSN) 1361-6587 (eISSN)

Vol. 56 3 035011

Areas of Advance


Subject Categories

Fusion, Plasma and Space Physics



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