Time: 2016-06-02 14:00:00
Speaker: Zhicheng Feng, Shengming Li [IFTS-ZJU]
Place: Rm. 413, Bld. 11#, Yuquan Campus
Abstract: Title: Study on Ion loss on Their First Orbits
Speaker: Zhicheng Feng
Abstract:
Neutral beam injection (NBI) is one of the widely used plasma heating method in tokamak. Fast ions come from NBI deposit near loss cone may be loss on their first bounce orbit due to wave particle interactions. In DIII-D experiment, it is found that the detected ion loss signal is of the same frequency of the wave in plasma. The loss ions may give energy to the wave, and no longer gain energy from wave even though they do not match the global resonant condition, since they are loss. R. B. Zhang etc. have studied the phenomenon in circular cross-section tokamak, and find a “local resonance condition”. Here, some numerical studies based on DIII-D equilibrium (146096) are performed with a given RSAE mode. The loss signals detected by fast ion loss detector (FILD) are calculated using the experiment NBI deposit data. The energy losses of the all loss particles are also calculated, and therefore the RSAE growth rate contributed by the loss ions is obtained. It is comparable to the earlier rough estimate by Heidbrink etc.
Title: Isotopic dependence of residual zonal flows
Speaker: Shengming Li
Abstract:
Self-generated zonal flows (ZF) play an important role in transport regulation in magnetic confinement devices. The isotopic dependence of confinement has been almost universally observed in tokamak experiments and there are also some analytic calculation results. So gyrokinetic linear and collisionless simulations using GTC code are carried out to study isotopic dependence of zonal flows.
First, the numerical results of residual ZF level are compared with Rosenblunth-Hinton(R-H)’s theory and Xiao-Catto(X-C)’s theory when considering only hydrogen.
Then, comparing hydrogen with deuterium, the results imply that the residual ZF level in deuterium plasmas can be stronger than those in hydrogen plasmas, and possibly lead to lower turbulence and transport.