Theory of Fine-scale Zonal Flow Generation From Trapped Electron Mode Turbulence

摘要

An important role of zonal DGows (ZF) in regulating turbulence and transport is now broadly accepted. Most gyrokinetic simulation studies highlighting the crucial role of ZFs concentrated on ion temperature gradient (ITG) turbulence. Since anomalous electron heat transport is ubiquitously observed from experiments even when the ITG mode seems stable, it's important to study ZF driven by trapped electron modes (TEMs). The collisionless TEM (CTEM) is driven by the trapped electron precession drift resonance, and is considered to be an important potential contributor to the electron anomalous transport in the core of fusion devices. Theoretical calculations of the nonlinearity associated with magnetically trapped electrons have been extensively investigated previously. The TEM driven turbulence and transport have also been studied experimentally in some tokamaks, such as ASDEX upgrade, Alcator C-Mod, and DIII-D.