Behaviour of turbulent transport in the vicinity of a magnetic island

The influence of a static magnetic island on the behaviour of the electrostatic turbulence in a tokamak is investigated numerically employing global nonlinear gyrokinetic particle-in-cell simulations. The excitation of turbulence is modified by the magnetic topology of the island. Low mode numbers in the energy spectrum of the potential disturbances, corresponding to the island perturbation, are amplified by nonlinear coupling with the microinstabilities, particularly in the presence of strong turbulence. The associated large-scale flows affect the transport directly and through strain of small-scale eddies. The temperature profile determined numerically in the island region agrees qualitatively with analytic estimates; however, quantitative discrepancies are found