Linear properties of global energetic particle induced geodesic acoustic mode with bump-on-tail distribution in tokamak plasmas

Abstract

A systematic study of the global Energetic particle-induced Geodesic Acoustic Mode (EGAM) has been carried out for bump-on-tail energetic distribution in tokamak plasmas using linear kinetic-fluid hybrid simulation. The stability threshold of EGAM in energetic particle pressure is found to be very low. The eigenmode structure becomes more and more radially extended as energetic particle distribution evolves from bump-on-tail distribution to fully slowing-down distribution. The mode radial scale length increases with the energetic particle orbit width.