Author: Miura Hideaki
Requested Type: Poster
Submitted: 2018-02-20 19:08:43
Co-authors: L.Zheng, W.Horton
National Institute for Fusion Science
Toki, Gifu 509-529
Two-fluid numerical simulations of interchange/tearing instabilities in 2D slab for edge plasma resistivity are carried out. The current diffusivity model which has developed by the authors [Phys. Plasmas 2017] to represent effects of stochastic magnetic field lines is adopted in this simulation research.
In the previous work, a numerical model with current diffusivity is developed 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), based on a fact that plasma outside the LCFS, or the scrape-off layer (SOL), is associated with open magnetic fields which terminate on the divertor plates in the outside. Our single-fluid MHD simulations have shown that interchange modes can transform into tearing modes, as the current-interchange tearing modes, as has been proposed by Zheng and Furukawa[Phys. Plasmas 2010, 2013].
In the present study, we pay attention to another nature of the edge plasma, a steep mass-density gradient. Because of the mass-density gradient, non-ideal MHD effects can alter the instability. We carry out two-dimensional simulations with the extended MHD model, together with the two-fluid (Hall) term and/or the gyro-viscous term. We show that the extension of the MHD model brings about an enhancement of flow, including diamagnetic flow, changing the saturation level of the instability and region of the influence of the current-interchange tearing modes.