Simulations of edge biasing and rotation in the C-2W FRC experiment using the Q2D code

We study the effects of end shorting and electrostatic biasing in simulations of the C-2W Field Reversed Configuration experiment using the Q2D code. Q2D is a 2D MHD code, which includes a neutral fluid and separate ion and electron temperatures, coupled with a 3D Monte Carlo code, which is used to calculate source terms due to neutral beams. The model includes the Hall term in Ohm’s law. We modified the boundary to impose different conditions on the radial electric field and we studied the effect of end shorting and electrostatic biasing. The shorting of open field lines at the external boundary generates a toroidal magnetic field and the propagation of a torsional Alfven wave. This modifies the radial electric field along the open field lines and makes the SOL plasma rotate in the ion diamagnetic direction. The plasma rotation can also be controlled by applying a finite radial electric field at the boundary to simulate the effect of electrode biasing. We observe the penetration of this rotation across the separatrix into the closed field lines by viscosity. The effect of the neutral beams on the rotation is also investigated.