Simulation Study on Nonlocal Transport for Peripheral Density Source

The simulation study of nonlocal transport for peripheral density source is performed using the 4-field reduced MHD model. A spherical density source is applied in the plasma edge, after saturation of the resistive ballooning turbulence is attained. After a while, the source is switched off. It is found that the nonlocal transport appears at the location far from the edge source, which induces not only (0,0) and (±1,0) modes but also finite n modes, where (m, n) indicates the set of poloidal mode number m and the toroidal mode number n. These modes interact with each other by the nonlinear and/or toroidal couplings. After switching-on the source, the formation of the spiral structure with poloidal rotation is observed, which yields a connection between core and edge regions. The simulation result indicates that 2D transport plays an essential role to the transient plasma response.