Impact of relative phase shift on inward turbulent spreading

Abstract

The relative cross-phase between density, temperature, and potential perturbations plays a major role in turbulent spreading and transport. Nonlinear Landau-Fluid simulations show that the electron wave-particle resonances provide a relatively strong parallel damping effect on the electron temperature perturbation and can induce a relative cross-phase shift of smaller than π∕2 angle between E × B velocity and the electron temperature perturbation for large electron temperature gradient, which yields a large spreading for electron. The relative phase for ions is about π∕2 and has no turbulent spreading effect on it. The inward turbulent spreading stops at the position where the radial turbulent correlation length is shorter than the magnetic surface spacing. The temperature pedestal height determines the energy loss due to the turbulent spreading.