Turbulent Multiscale Interactions between Tearing Modes, Trapped-Electron Modes, and Zonal Flows

Interactions between MHD-scale tearing modes (TMs) and ion-gyroradius-scale trapped-electron modes (TEMs) in a fusion plasma are simulated with global gyrokinetics, using a consistent set of fixed equilibrium profiles. Unstable core TMs nonlinearly couple and transfer energy to smaller-scale stable TMs near the edge, where TEMs are present. Magnetic stochasticity from these edge TMs erodes TEM-generated zonal flows near the edge rational surfaces, leading to strongly increased electrostatic flux. This interaction of macro- and microscale modes suggests it may be possible to control microturbulence through current-profile modifications.