9月23日 Gyrokinetic simulation of excitation of low frequency Alfven eigenmodes and nonlinear interaction between BAE and BAAE

　　题  目：Gyrokinetic simulation of excitation of low frequency Alfven eigenmodes and nonlinear interaction between BAE and BAAE

　　报告人：  Yaqi Liu  (北京大学)

　　时  间：2016年9月23日（星期五）  9:30—10:30

　　地  点：六楼中间会议室

　　摘  要：

　　GTC simulations find that beta-induced Alfven Acoustic eigenmode (BAAE) can be excited by realistic energetic particle density gradient, even though the stable BAAE (in the absence of energetic particles) is heavily damped by the thermal ions. This is found due to nonlocal and non-perturbative effects. When we decrease the tokamak size ITER to present-day tokamak, the most unstable modes change from BAAE to BAE (beta-induced Alfven eigenmode). For a certain tokamak size, BAE and BAAE coexist with similar linear growth rates. At nonlinear stage, BAE modes saturate first, while BAAE modes continue to grow until nonlinear modes with beating wave (sum of BAE and BAAE frequency) and positive frequencies are excited. GTC simulations current-driven instability including kink and tearing modes will also be discussed.

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