Two-fluid edge-plasma SOL turbulent transport driven by interchange/tearing instabilities

Two-fluid numerical nonlinear simulations of interchange/tearing instabilities in a 2D slab for edge plasma are carried out. The current diffusivity model describes the effects of the stochastic magnetic field linesformedin the simulations. Current diffusivity develops to enforce a low-level saturated current profile in the SOL region as well as a current jump across the Last Closed Flux Surface (LCFS). plasma outside theLCFS is on open magnetic fields terminating on the divertor plates. Earlier single-fluid MHD simulations have shown that interchange modes transform into tearing modes forming mixed current-interchange tearing modes. New simulations show how the steep edge plasma mass-density gradients bring in two-component FLR-Hall MHD effects that limit the turbulence level. We carry out two-dimensional simulations with the two-fluid (Hall) term and the gyro-viscous term. The extended FLR-Hall-MHD model brings about enhanced plasma flows, including diamagnetic flows, and reduces the saturation level of the turbulence while mixing the influence of the current-interchange tearing modes.

H. Miura, L.Zheng, W. Horton,“Numerical simulations of interchange/tearing instabilities in 2D slab with a numerical model for edge plasma”, Phys. of Plasmas 24, 092111 (2017)

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