'Transmitted-wave' boundary condition for the wave equation multiscale computation of electromagnetic waves

We present in this paper a boundary condition solving the wave equation at the interfaces of connected grids having arbitrary resolution. This algorithm applies to the finite-difference form of the wave equation and has been developed for the computation of electromagnetic fields on a multiple spatial scale level domains. Because this algorithm is local and explicit, it allows domain decomposition with efficient scaling of run time on parallel computers. This algorithm is being implemented in the 3D electromagnetic Particle-In-Cell code BPIC3D for beam transport calculations in Heavy-Ion Inertial Fusion [1].