Broadband SIBC Formulation for a Low-Dispersion Finite Volume Method in the Time Domain

Surface impedance boundary conditions for the computation of resistive wall wakefields in linear accelerators are developed. The method represents an extension of the staggered finite volume method in the time domain (SFVTD) for the discretization of Maxwell's equations. It uses an auxiliary differential equation formulation for general impedance functions describing the frequency-dependent wall conductivity, surface roughness, or metal oxidation. For the time discretization of the resulting dispersive equations, a particular technique based on exponential integration is employed. This allows us to preserve the basic properties of the SFVTD method such as unidirectionally optimal numerical dispersion and maximum stability bound, which are of crucial importance for electromagnetic wakefield computations.