## Abstract

The effects of finite drift orbit width (FOW) and Larmor radius (FLR) of fast particles on the stability of low-n toroidicity-induced Alfvén eigenmodes (TAE) are studied. The formulation is based on the solution of the low frequency gyrokinetic equation (ω<ω_{c}, where ω_{c} is particle cyclotron frequency). A quadratic form has been derived in terms of invariant variables; energy ε, magnetic moment μ, and toroidal angular momentum P_{φ}. The growth rate of the TAE is computed perturbatively using numerical averaging over the fast particle drift orbit. This new computational capability improves the NOVA-K code [G. Y. Fu, C. Z. Cheng, and K. L. Wong, Phys. Fluids B 5, 4040 (1994)] which included FOW effects in the growth rate calculation based on small radial orbit width approximation. The new NOVA-K version has been benchmarked for different regimes of particle TAE excitation. It is shown that both FOW and FLR effects are typically stabilizing; the TAE growth rate can be reduced by as much as a factor of 2 for tokamak fusion test reactor supershots [D. J. Grove and D. M. Meade, Nucl. Fusion 25, 1167 (1985)]. However, FOW may be destabilizing for the global modes, which are localized at the plasma edge

Original language | English |
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Pages (from-to) | 2802-2807 |

Number of pages | 6 |

Journal | Physics of Plasmas |

Volume | 6 |

Issue number | 7 |

DOIs | |

Publication status | Published - 1999 Jan 1 |

## All Science Journal Classification (ASJC) codes

- Condensed Matter Physics