The Interaction Process Between Alfven Waves And High Energy Particles

Physicists find many unstable modes, when they target high steady-state parameters operation in tokamak. For example, there are some unstable modes while alfvén wave propagates in tokamak plasmas. The ?TAE( ?-induced Toroidal Alfvén Eigenmode,?=-q2Rd?/dr,q is safety factor, ? is ratio of plasma to magnetic pressures)is one of the alfvén modes. It has been found?TAE can exist in tokamak devices in theory. Based on high-n ballooning mode formalism and the(s, ?) model equilibrium, we investigate ?TAE by using a linear gyrokinetic-MHD hybrid simulation code.In simulation discharge of KSTAR, we find the distribution of ?TAEs is very extensive along the normalized minor radius, different configurations of safety factor in KSTAR tokamak have a closely influence on the distributing situation of the ?TAEs. In simulation discharges of EAST, people expect the large pressure gradient of plasma produces the bootstrap current, but it induces the ?TAE as the same time.In this discharge, NBI is used for the plasma heating and the plasma current driving. NBI(Neutral Beam Injection)certainly helps the number of energetic particles increase, and the energetic particles could destabilize the ?TAE and downgrade the tokamak confinement.