title: Small-action particles in a tokamak in the presence of an n = 1 mode
abstract: It is found that an m = n = 1 mode with amplitude exceeding a certain threshold can lead to stochastic motion of energetic ions in tokamaks, the large orbit width particles (potatoes) being most easily affected. An n = 1 mode can redistribute particles also in the absence of stochasticity but only when the perturbation is quickly switched on/off, e.g., during a sawtooth crash. In the latter case, the perturbation results in a regular motion of particles around a certain helical orbit, at which a resonance driven by the mode but having no amplitude threshold takes place.
authors.affiliation: Scientific Centre "Institute for Nuclear Research," Kyiv, 252680, Ukraine.
authors.initials: YI
authors.lastname: Kolesnichenko
authors.initials: VV
authors.lastname: Lutsenko
authors.initials: RB
authors.lastname: White
authors.initials: YV
authors.lastname: Yakovenko