Modeling RF-induced ponderomotive effects on edge/SOL transport with UEDGE and Vorpal

EM fields driven by ICRF antennas in the tokamak plasma edge, injected to heat the core plasma, also give rise to transport-timescale ponderomotive effects. Together with the conventional grad(v^2) ponderomotive force, additional terms dependent on density gradients, species charge signs, collisionality, and incident wave polarization may arise; these introduce additional vorticity, energy, and parallel momentum sources to the edge/SOL transport. For large antenna input powers and edge density gradients (e.g. H-mode), RF-induced ponderomotive physics may be large enough to appreciably influence edge plasma dynamics, e.g. by expelling density from, or inducing convective cells in, the region near the antenna. We investigate these effects using Vorpal (FDTD EM+plasma solver) and UEDGE (2D edge plasma transport code). Contributions of various source terms (vorticity, energy, momentum) are assessed with independent UEDGE and Vorpal simulations. RF-induced parallel momentum is estimated to exert greater influence on edge/SOL dynamics than vorticity/energy sources are in representative ICRF heating scenarios. Detailed calculations with the RF parallel momentum source, in which Vorpal and UEDGE are coupled in 2D, explore and quantify the roles its effects might play in edge transport.