Time: 2016-11-10 14:00:00
Speaker: Xishuo Wei [IFTS-ZJU]
Place: Rm. 413, Bld. 11#, Yuquan Campus
Abstract: Title: Validation of quasilinear diffusion by electron Landau damping in toroidal geometry
Speaker: Xishuo Wei (魏西硕)
Abstract: We study the conditions to validate quasilinear diffusion by electron Landau damping in toroidal geometry. As an example, the Landau damping by lower hybrid waves in a tokamak is considered. A particle code is used to calculate particle motion in phase space, and the diffusion coefficient in parallel direction is given by Dql=⟨Δv2⟩/(2Δt) over a period of time. For simplicity, the particle motion is perturbed by the electrostatic waves only in the parallel direction, and the perpendicular motion is not taken into account in the diffusion coefficient with the assumption of significantly small gyro-radius and orbit width compared to the perpendicular wavelength. The variation of parallel velocity due to the varying magnetic field in a flux surface is considered to include the effect of the toroidal geometry on the diffusion coefficient. The calculated coefficient is compared with the theoretical value of bounce-averaged Kennel-Engelmann(K-E) quasilinear diffusion coefficient.