Tuesday, September 25, 2018
Recent numerical results demonstrated that the interaction between ion-scale and electron-scale turbulence in tokamaks plays an important role in setting the overall level of energy transport (Howard et. al, 2015). One of the potentially important cross-scale interaction mechanisms is the inverse cascade of energy from electron scales to ion scales driven by unstable electron-temperature-gradient (ETG) modes. This inverse cascade mechanism is not understood. We present preliminary results from numerical and analytical studies aimed at elucidating the potentially important role of the inverse cascade of magnetic helicity injected by ETG modes. The studies were performed in slab geometry, using a reduced gyrokinetic model (Zocco and Schekochihin, 2011).