A current-driven electromagnetic mode in sheared and toroidal configurations

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

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


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 languageEnglish (US)
Article number035011
JournalPlasma Physics and Controlled Fusion
Issue number3
StatePublished - Mar 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics


  • current gradient
  • gyrokinetic
  • instability
  • kink mode
  • simulation


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