### 摘要

Fusion-born α particles moving parallel to the magnetic field can resonate with toroidal Alfvén eigenmodes (TAE) leading to anomalous α-orbit diffusion across the α-loss boundaries in a tokamak. This is analyzed using the Hamiltonian guiding center code ORBIT in conjunction with the kinetic magnetohydrodynamics (MHD) eigenmode solving code NOVA-K. Resonant single a orbits are studied below and above the threshold for orbit stochasticity and Monte Carlo randomized ensembles of alphas subjected to a finite amplitude time-dependent TAE are followed with respect to their radial losses using realistic MHD equilibria and numerically computed toroidal Alfvén eigenfunctions for one toroidal eigenmode n = 1 and the full Fourier spectrum of poloidal harmonics m involved in the "gap mode." The α-loss mechanisms are resonant drift motion across the loss boundaries of alphas born near these boundaries and stochastic diffusion to the boundaries in constants of the motion (phase) space. After a first transient of resonant drift losses scaling as B̃_{r}/B_{0}, the number of alphas lost via diffusion scales as (B̃_{r}/B_{0})^{2}. For TAE amplitudes B̃_{r}/B_{0}≥10^{-3}, α orbit stochasticity sets in and, depending on the radial width of the fast α density n_{α} (r), a substantial fraction of alphas can be lost in one slowing down time. For B̃_{r}/B_{0}<10 ^{-4}, the losses become insignificant.

原文 | English |
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頁（從 - 到） | 1506-1516 |

頁數 | 11 |

期刊 | Physics of Fluids B |

卷 | 4 |

發行號 | 6 |

DOIs | |

出版狀態 | Published - 1992 一月 1 |

### All Science Journal Classification (ASJC) codes

- Computational Mechanics
- Condensed Matter Physics
- Mechanics of Materials
- Physics and Astronomy(all)
- Fluid Flow and Transfer Processes

## 指紋 深入研究「Alpha-particle losses from toroidicity-induced Alfvén eigenmodes. Part II: Monte Carlo simulations and anomalous alpha-loss processes」主題。共同形成了獨特的指紋。

## 引用此

*Physics of Fluids B*,

*4*(6), 1506-1516. https://doi.org/10.1063/1.860061