Time: Thursday, Dec. 16th, 4:00pm
Speaker: Ningfei Chen
Title: Gyrokinetic theory of the parametric decay of the Alfvenic ion-temperature gradient driven mode in the non-uniform plasmas
Abstract:
Alfvenic ion-temperature gradient driven mode (AITG) is an ion-temperature driven shear Alfven (SA) instability, with the frequency being comparable to the ion diamagnetic frequency ω_*pi and much smaller than that of the SA wave ω_A. Due to its peculiar feature of rendering the transport of both thermal and energetic particles (EPs), tens of publications have been devoted to the experimental observation, theoretical investigation and numerical simulation of the AITG since 1990s. In addition, in the future tokamaks with typically high-β, β is the ratio between the thermal and magnetic pressure, the electromagnetic effect is important, e.g., it stabilizes electrostatic ITG mode, while, destabilizes electromagnetic AITG mode. Thus, the nonlinear interactions of the AITG are required to understand the spectrum evolution and associated transport.
More importantly, Di Siena et al observed in the simulation that the EPs stabilized ITG mode via nonlinear interaction between the ITG and SA waves driven by the EPs, possibly AITG. But, the mechanism of the nonlinear interaction is still not understood. Therefore, in this work, the parametric decay of the AITG into its sideband and ITG is systematically investigated in the nonlinear Gyrokinetic framework. This work is a natural extension of [L. Chen, EPL, 2011], which investigates the kinetic Alfven wave decays into its sideband and ion sound wave in the slab geometry, into non-uniform plasmas in the toroidal geometry. On the one hand, the work is still undergoing, the progresses and challenges are going to be clarified in this talk. On the other hand, some related papers will be reviewed to fulfill the background of the audiences.
Speaker: Guangyu Wei
Title:Calculation of neoclassical inertia enhancement factor in the linear dispersion relation of zonal flow
Abstract:
Recently, I did some literature searching, and repeated the calculation of neoclassical inertia enhancement factor χ_z∝1.6 q^2∕√ϵ, known to most of us in the linear dispersion relation of zonal flow, which was firstly given by Rosenbluth and Hinton in 1998. Here, I will briefly share the detailed calculation.
由于疫情原因,本次报告在钉钉群线上举行