Computation of Ponderomotive Force in 3D FDTD Simulation

We present a detailed mathematical analysis of the tensor Ponderomotive Force calculation in 3D, from fundamental principles. We are primarily interested in applications of this to tokamak configurations with ICRF, helicon, and/or LH RF sources. The tensor analysis includes force terms in both the poloidal plane and in the toroidal plane, which can result in either perpendicular force x B poloidal-plane convection or parallel force that can lead to rarefaction, or other toroidal displacements when coupled with an equilibrium code. We also present the implementation of the tensor ponderomotive force calculation in a 3D finite-difference time-domain (FDTD) simulation tool (VSim [1]) which can model 3D antenna and launcher geometry. We verify the implementation on a simple test case. We also discuss processing the 3D vector force for use in equilibrium and turbulence codes.