Multi-scale turbulence and isotope effects on the trapped electron mode
Tomo-Hiko Watanabe
Nagoya University
Department of Physics
Plasma turbulence consists of multiple spatiotemporal scales, originating from difference of electron and ion mass. It has been revealed that the electron temperature gradient (ETG) turbulence excited in the electron gyroradius scale may interact with turbulence driven in the ion-gyroradius scale, such as the ion temperature gradient (ITG) mode and the micro-tearing mode (MTM). We have also confirmed cross-scale interactions of the trapped electron mode (TEM) and the ETG turbulence, where growth rate reduction of the former is explained by an effective diffusion caused by the latter. A theoretical model of the effective diffusion is verified by the multi-scale simulation, and is implemented to the gyrokinetic simulation of the TEM turbulence. It is also found that the effective diffusion brought by the ETG turbulence may enhance the isotope effect on the TEM turbulent transport through the collisionarity dependence.