时间：周四，3月16日，15:30
地点：海纳楼8幢324
报告人：刘朝阳
题目：A Simple Model for Internal Transport Barrier Induced by Fishbone in Tokamak Plasmas
摘要：
Fishbone bursts have been observed to strongly relate to internal transport barrier (ITB) formation in a number of tokamak devices. A simple model incorporating the fishbone bursts dynamics and ion pressure gradient evolution is proposed in order to investigate the key physics parameter assisting triggering ITB. The time evolution of fishbone could be described by the well-known predator-prey model. For each burst cycle, the energetic particles (EP) resonantly interact with fishbone and are radially expelled leading to a radial current. A compensating bulk plasma return current and hence poloidal flow can be build up on condition that the fishbone cycle frequency is greater than the poloidal flow damping rate. When the shear of the flow exceeds a critical value, the turbulent fluctuations are suppressed and the ion pressure gradient accesses to the high confinement state. It is shown that this process is only sensitive to the deposition rate of trapped EP within the q=1 surface, but not sensitive to other parameters. A quantitative formula to estimate the shearing rate of poloidal flow induced by fishbone bursts is derived and numerically verified.
报告人：童彦轩
题目：大气放电中的高能辐射
