Two-dimensional finite-boxes analysis of monopolar corona fields including ion diffusion

A novel numerical technique is presented for computing the field of a system of monopolar coronating electrodes. The physical model is based on the Poisson and continuity equations; ion diffusion is allowed for and Kapzov´s boundary conditions are imposed on the emitter. Discretization is performed through a mixed finite-boxes FEM (finite-element method) scheme, and the nonlinear system thereby obtained is solved in coupled form by Newton´s method. Including ion diffusion improves the physics of the model and allows the continuity equation to be discretized through powerful, spurious-solution-free schemes, thereby improving the convergence properties of the algorithm from a poor initial guess. Numerical results are presented for one- and two-dimensional geometries