Shearing Alfven Waves Excited By High-energy Particles

Alfvén waves play a critical role in the research of magnetic confinement fusion burning plasmas.Several kinds of Alfvén eigenmodes are found in the theory and experiments.Those modes can be destabilized by energetic particles via wave-particle resonances.A new type of Alfvén eigenmodes is termed as discrete Alfvén eigenmodes(?TAEs,with ? being a measure of plasma pressure gradient)in the high-beta toroidal plasma.?TAEs trapped in the ?-induced potential well due to the pressure gradient and ballooning curvature effects,which have been discovered in second ballooning stable and the reversal magnetic shear region.In recent years,it has been reported that the instability of multiple Alfvén eigenmodes are excited by energetic particles in HL-2A,such as the toroidal Alfvén eigenmode(TAE),beta-induced Alfvén eigenmodes(BAE),high-frequency reversed shear Alfvén eigenmodes(HFRSAE).In order to control and optimize the plasma current profile,there are various schemes of auxiliary heating and current drive in the HL-2A tokamak.The energy input by the process of auxiliary heating is deposited in the different regions in the directions of the small radius of the Tokamak.In the regions,the increase of the temperature of plasma may produce greater gradient of plasma pressure.Basing on HL-2A tokamak,applying a magnetohydrodynamic(MHD)simulate codes,we study the characteristics of discrete Alfvén eigenmodes(?TAEs,? is a measure of plasma pressure gradient)in the power deposition region of lower hybrid wave auxiliary heating scheme.We explore the distribution of ?TAE upon varied different plasma profiles.Employing gyrokinetic-MHD hybrid simulate codes,we investigate ?TAE kinetically excited by energetic particles produced by neutral beam injection.Furthermore,we study physical characteristics of ?TAE destabilized by energy particles in the lower hybrid wave power deposition region.In addition,in order to utilize fusion energy,people researches on tokamaks provide theoretical,technical,engineering feasibility for China Fusion Engineering Test Reactor(CFETR)and International Thermonuclear Experimental Reactor(ITER).Based on tokamaks inthe world,applying a magnetohydrodynamic(MHD)simulate codes and gyrokinetic-MHD hybrid simulate codes,we investigate the stability characteristic of?TAEs in different types of tokamaks.Moreover,the physical features of ?TAEs are studied under the condition of energetic particles produced in burning plasmas.we find that there exist ?TAEs in HL-2A tokamak with relatively small ? values.Besides,the ?TAEs are mainly distributed in the reversal magnetic shear region.There are the abundant ?TAEs in the lower hybrid wave power deposition region,where the amount of lower hybrid wave power deposition is greater.Moreover,with different plasma profiles,abundant ?TAEs are found in the different region in the directions of the small radius of the HL-2A tokamak.With the increase of the neutral beam injection energy,the multiple branches of ?TAEs are developed kinetically into unstable modes.It's also find that there exist ?TAEs,in extended operate region,which are kinetically destabilized by energetic particles.which may potentially affect the plasma confinement of tokamak and the steady-state operation of future fusion reactor.