Alfvén Characteristic Behavior In Tokamak

Discrete Alfvén eigenmodes(i.e.,αTAEs,with α being a measure of plasma pressure gradient),within the magnetohydrodynamic(MHD)description,are quasi-marginally stable modes,which can be readily destabilized by energetic particles in burning plasmas.These kinetically unstable modes could potentially affect steady-state operations of tokamaks.In this paper,we describe the kinds of devices for controlled nuclear fusion,and the physical characteristic of shear Alfvén wave andαTAE,then,discuss the simulation program of αTAEs.What’s more,the stability features of αTAEs are delineated upon the(s,α)equilibrium model.Their multiple branches are demonstrated with MHD computations as well as MHD-gyrokinetic hybrid simulations.The kinetic excitations are presented for the αTAEs via wave-particle resonances.These αTAEs instabilities are also discussed for varied tokamaks.Here,we focus on the relationship between αTAEs and bootstrap current with a MHD simulation code and a gyrokinetic-MHD hybrid simulation code in two typical scenarios in ITER,and compare these typical scenarios with two ordinary scenarios about physical characteristics of αTAEs.These αTAEs are always lying in the region of high bootstrap current.However,they are not corresponding absolutely in pure radio frequency scenario(one of typical scenarios)because of large-α.Moreover,we illustrate the multiple branches of αTAEs in those typical scenarios,and find high-order modes trapped by the lower potential well.αTAEs exist widely in ITER scenarios with bootstrap current However,αTAEs are quasi-marginally stable in MHD description and could be readily destabilized by energetic particles in hybrid simulation via wave-particle resonances.