This work is concerned with a study of possible effects of turbulent electrostatic waves on trapped particle motions in low-β toroidal plasmas. A mechanism of resonance between the frequencies of the waves in the turbulent spectrum and the harmonics of the particle bounce frequency in the magnetic wells is found to provide stochastic trapped particle diffusion. The effectiveness of this diffusive process in scattering trapped particles out of the trapping cone in velocity space has been investigated in detail as functions of the wave features and of the particle parallel energy for the cases of ion sound waves and of different types of drift waves. The conclusions are that an electrostatic turbulence of a relatively low level, with typical frequencies higher than the bounce frequency and wavelengths shorter than the connection length, can be effective in scattering trapped electrons out of the trapping cone in typical times longer than the bouncing time but still shorter than collisional times. On the other hand, similar effects cannot be obtained easily for the ions, owing to their greater inertia.
This work is concerned with a study of possible effects of turbulent electrostatic waves on trapped particle motions in low-β toroidal plasmas. A mechanism of resonance between the frequencies of the waves in the turbulent spectrum and the harmonics of the particle bounce frequency in the magnetic wells is found to provide stochastic trapped particle diffusion. The effectiveness of this diffusive process in scattering trapped particles out of the trapping cone in velocity space has been investigated in detail as functions of the wave features and of the particle parallel energy for the cases of ion sound waves and of different types of drift waves. The conclusions are that an electrostatic turbulence of a relatively low level, with typical frequencies higher than the bounce frequency and wavelengths shorter than the connection length, can be effective in scattering trapped electrons out of the trapping cone in typical times longer than the bouncing time but still shorter than collisional times. On the other hand, similar effects cannot be obtained easily for the ions, owing to their greater inertia. この研究は、低βトロイダルプラズマにおける捕捉粒子運動に対する乱流静電波の可能的影響の研究に関するものである。乱流スペクトル中の波の周波数と、磁気井戸内の粒子のバウンス周波数の高調波との間の共鳴機構が、確率的捕捉粒子拡散をもたらすことが見出された。速度空間において捕捉粒子を捕捉円錐の外へ散乱させる際のこの拡散過程の有効性について、イオン音波および異なる種類のドリフト波の場合について、波動の特性と粒子の平行エネルギーの関数として詳細に調査した。結論として、バウンス周波数より高い典型的周波数と接続長より短い波長を持つ、比較的低レベルの静電乱流は、バウンス時間より長いが衝突時間よりは依然として短い典型的時間で、捕捉電子を捕捉円錐の外へ散乱させるのに有効であり得る。一方、イオンについては、その大きな慣性のため、同様の効果を容易に得ることはできない。