Simulation Study Of Alfv(?)n Eigenmode Instability And Energetic Particle Transport For Tokamaks

Energetic particle(EP)generated by fusion reaction or auxiliary heating could interact with the Alfven Eigenmodes(AEs)in Tokamak.EP transfer the free energy to the AEs by wave-particle resonance,which could destabilize the AEs.In contrast,the unstable AEs drive the EP transport and make EP redistribute in space.Thus,the investigation about EP and AE are divided into the two parts.AEs are driven unstable by on-axis neutral beam(NB)injection in DIII-D reversed magnetic shear discharges#166496 and#159243,a high-beta steady-state demonstration discharge and an L-mode current ramp discharge respectively.The experimental results are used to validate the ideal MHD code with kinetic extensions NOVA-K and the gyro-Landau-fluid code TGLFEP.Both codes predict low toroidal mode number(n=1?2)Toroidal Alfven Eigenmode(TAE)instability in the former discharge and low-n(n=2?6)Reverse Shear Alfven Eigenmode(RSAE)instability in the latter discharge,consistent with observations.The same two codes are also employed to predict linear AE instabilities driven by a particles in the China Fusion Engineering Test Reactor(CFETR).For the CFETR reversed shear q profile,the growth rates of AEs change periodically with increasing toroidal mode number and the RSAEs near a rational surface always have larger growth rates than TAEs.AEs are found to be further destabilized by addition of 500keV off-axis injected NB.The effects of q-profile variation on AE stability in CFETR are also investigated and the results show that raising qmin.can further destabilize RSAEs,while increasing q0 with fixed qmin,to create stronger negative magnetic shear,is stabilizing.Increasing plasma density is beneficial for AE stability due to reduced fast ion drive because of shorter slowing down time and higher electron collisional damping.Energetic particle transport is investigated by the kinetic transport code EPtran,which is based on critical gradient model.The key input of the code is the EP critical gradient obtained by the TGLFEP.The accuracy of the TGLFEP is validated by the NOVA-K on DIII-D#142111 discharge 525ms.The simulation result of the EP radial pressure profile is similar to the diagnostic result,except the region near the edge.Since the code only consider the effect of turbulence on EP transport near the edge,the simulation result is larger than diagnostic.Next,the same method is used to predict a particle transport on CFETR steady-sate and hybrid operation.On steady-state operation,the unstable TAE drive a particle transport,which is driven by unstable BAE on hybrid operation.The comparison between two operation exhibit that the width of high a particle pressure gradient is narrow,and the radial position of the AEs are close on hybrid operation,therefore the effect of AE on EP transport is weaker and the EP density is higher in the core since the original EP density of hybrid operation is higher.