Simulation of energetic particle driven geodesic acoustic modes and the energy channeling in the Large Helical Device plasmas

Abstract

Energetic particle driven geodesic acoustic modes (EGAMs) in Large Helical Device plasmas are investigated using MEGA code. MEGA is a hybrid simulation code for energetic particles interacting with a magneto-hydrodynamic (MHD) fluid and in the present work, both the energetic particles and bulk ions are described by the kinetic equations. The low frequency EGAMs are reproduced. Also, the energy transfer is analyzed and the bulk ion heating during the EGAM activity is observed. The ions obtain energy when the energetic particles lose energy, and this indicates that an energy channel is established by the EGAM. EGAM channeling is reproduced by simulation with realistic parameters for the first time. The heating power to bulk ions is 3.4 . It is found that sideband resonance is dominant during the energy transfer from EGAM to the bulk ions, and the transit frequencies of resonant bulk ions are one-half of the EGAM frequency.