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Gyrokinetic theory of the nonlinear saturation of toroidal Alfven eigenmode

Date: 2019-01-17
Time: 10:15
Venue: 中国科学院物理研究所A楼3层会议室
Speaker: 仇志勇博士

(IFTS,Zhejiang University)


In burning plasmas of next generation tokamak devices such as ITER , energetic particles(EP), e.g. fusion-alpha particles, contribute significantly to the total power density and, consequently, could drive shear Alfven wave (SAW) instabilities . SAW instabilities, in turn, can lead to enhanced EP transport, degradation of plasma performance and, possibly, damaging of plasma facing components . Due to equilibrium magnetic field geometries and plasma non-uniformities, SAW instabilities manifest themselves as EP continuum modes (EPM) and/or various discretized Alfven eigenmodes (AE); e.g., the well-known toroidal Alfven eigenmode (TAE) . The EP anomalous transport rate is related to TAE amplitude and spectrum, and thus, in-depth understanding of the nonlinear dynamics of TAE is crucial for assessing the performance of future burning plasmas

In this topic, I will present the investigation of nonlinear saturation of TAE via ion induced scatterings in the short-wavelength gyrokinetic regime. It is found that the nonlinear evolution depends on the thermal ion beta value. Here, beta is the plasma thermal to magnetic pressure ratio. Both the saturation levels and the associated energetic-particle transport coefficients are derived and estimated correspondingly.