We derive a self-consistent relation between turbulence spreading flux and vortex flow acceleration for time-stationary turbulence inside a magnetic island (MI) by extending the Charney-Drazin momentum theorem. The result, which consists of flux-surface-averaged expressions with geometrical weight, indicates a dominant balance between the turbulence spreading flux through regions around X-points and the vortex flow away from the X-points on the same flux surface. This is in qualitative agreement with experimental observations from DIII-D, KSTAR and HL-2A.
This paper explains how turbulence spreading can drive vortex flow generation within magnetic islands, which is important for understanding plasma confinement in fusion devices.