Cooling and transport of energetic ions due to the global geodesic acoustic mode

Abstract

It is shown that (i) the destabilization of global Geodesic Acoustic modes (GAM or E-GAM) by passing energetic ions in tokamaks can be accompanied with a considerable energy transfer from these ions to the mode; (ii) the mode-induced slowing down of the energetic ions leads to a radial shift outwards/inwards of the ions moving in the direction counter to/of the plasma current, in spite of the fact that the canonical angular momentum of the particles is conserved during GAMs. Some practical consequences of these phenomena are discussed. • Global GAM modes lead to radial displacements of the resonant energetic ions. • Radial displacements of energetic ions driving the GAM instability is associated with their cooling during this instability. • Spatial channeling of the energy and momentum of fast ions is possible due to GAM modes. • Spatial channeling by the GAM mode tends to make the radial profile of the plasma heating more peaked.