Nonlinear MHD study on the influence of E\texttimes B flow in QH-mode plasma of DIII-D

In~QH-mode experiments with zero-net NBI torque show that there remains~a finite~E\texttimes B rotation in the pedestal region implying that a minimum~E\texttimes B flow or flow shear is required for the plasma to develop the Edge Harmonic Oscillation (EHO), which is a saturated KPM (kink-peeling mode)~characteristic of the QH-mode. To understand the roles of E\texttimes B flow and its shear in the saturation of KPMs,~non-linear MHD simulations~of DIII-D QH-mode plasmas including toroidal mode numbers n $=$ 0 to 10 with different E\texttimes B rotation speed have been performed. These simulation show that ExB~rotation strongly stabilizes high-n modes but destabilizes low-n modes (particularly the~n$=$2 mode) in the linear growth phase, which is consistent~experimental observations and previous linear MHD modelling.