Kinetic theory of helical instabilities in a cylindrical tokamak

S. Inoue Itoh, K. Itoh

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Abstract

The kinetic theory of the drift-tearing mode in a finite-β, collisionless inhomogeneous cylindrical tokamak is investigated. It is found that 1) when the density is low, the kinetic drift-tearing modes are unstable whereas they become stabilized as the density increases, 2) the medium-m (poloidal mode number) modes have a smaller growth rate, and 3) the electron temperature gradient further stabilizes these modes. Because of the magnetic shear and the finite β value, the outgoing drift wave is associated with the tearing mode, and hence the ion Landau damping stabilizes the mode when β increases. The local current density is found to be crucial for the instability. It is noted that the stability criterion for the MHD tearing mode, [formatted text] is the jump of the logarithmic derivative of Br across the mode rational surface), is lo longer valid for kinetic tearing mode. - For future tokamak parameters, low- and medium-m (2 ≤m ≲ 50) kinetic drift-tearing modes are found to be stable in cylindrical geometry.

Original languageEnglish
Pages (from-to)3-13
Number of pages11
JournalNuclear Fusion
Volume21
Issue number1
DOIs
Publication statusPublished - Jan 1981

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All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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