### 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 B_{r} 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 language | English |
---|---|

Pages (from-to) | 3-13 |

Number of pages | 11 |

Journal | Nuclear Fusion |

Volume | 21 |

Issue number | 1 |

DOIs | |

Publication status | Published - Jan 1 1981 |

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### All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics
- Condensed Matter Physics

### Cite this

*Nuclear Fusion*,

*21*(1), 3-13. https://doi.org/10.1088/0029-5515/21/1/001

**Kinetic theory of helical instabilities in a cylindrical tokamak.** / Itoh, Sanae; Itoh, K.

Research output: Contribution to journal › Article

*Nuclear Fusion*, vol. 21, no. 1, pp. 3-13. https://doi.org/10.1088/0029-5515/21/1/001

}

TY - JOUR

T1 - Kinetic theory of helical instabilities in a cylindrical tokamak

AU - Itoh, Sanae

AU - Itoh, K.

PY - 1981/1/1

Y1 - 1981/1/1

N2 - 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.

AB - 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.

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U2 - 10.1088/0029-5515/21/1/001

DO - 10.1088/0029-5515/21/1/001

M3 - Article

VL - 21

SP - 3

EP - 13

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 1

ER -