Simulation of abrupt massive migrations of energetic beam ions in a tokamak plasma

The resonant excitation of MHD waves plays an important role for the confinement and transport of energetic ions in MCF plasmas. This presentation reports recent advances that were made in simulating these wave-particle interactions numerically using a hybrid model, which includes realistic beam ion sources and beam-bulk collisions, so that it is valid over a wide range of time scales: from Alfvenic oscillations (μs scale) to collisional slow-down (>100 ms). In order to be able to simulate the long-time evolution on available supercomputers, the so-called multi-phase method is employed. We show that this method allows us to reproduce multiple cycles of so-called abrupt large-amplitude events (ALE), as seen in JT-60U. The latest insights on ALE physics obtained with such simulations are discussed. Particular attention will be given to the role of multi-dimensional phase space transport, retardation effects, and the possibility of magnetic reconnection being driven by large amplitude MHD waves.Kyoto Workshop on Nonlinear Wave Particle Interactions in Plasma