Alternating-order interpolation in a charge-conserving scheme for particle-in-cell simulations

We discuss the interpolation of the electric and magnetic fields within a charge-conserving Particle-In-Cell scheme. The choice of the interpolation procedure for the fields acting on a particle can be constrained by analyzing conservation of the energy and the particle generalized momentum. The better conservative properties are achieved, if the alternating-order form-factor is used for interpolation, which combines the lower-order and higher-order interpolation from integer and semi-integer points of a staggered grid. This approach allows us to significantly improve both the quality of results and the computational efficiency for the charge conserving scheme.