Particle distribution modification by magnetohydrodynamic modes

It is known that low amplitude magnetohydrodynamic (MHD) modes can produce modification of high energy particle distributions, and also significant losses.\footnote{R. B. White, N. Gorelenkov, W. W. Heidbrink, and M.A. Van Zeeland {\em Plasma Physics and Controlled Fusion}, 52 045012 (2010)} This phenomenon is important particularly for the redistribution of alpha particle distributions in burning plasmas. Methods are examined for predicting the stochastic onset of large scale transport of a high energy particle distribution in tokamak plasmas due to a spectrum of MHD modes. The phase space of particle orbits is modified by resonant modes by the production of islands in which particles are trapped in the wave. When these islands overlap stochastic trajectories are made possible leading to large scale motion of the particles. Predicting the location and extent of the resonant islands and stochastic domains can lead to a rapid understanding of the proximity of global avalanche.