Numerical particle heating and diffusion correlated to interpolation-induced divergence in a static magnetic field for PIC simulations

Non-physical heating and diffusion resulting from interpolation of a discretized magnetic field are examined for the case of moderate normalized divergence, η = L₀(Δ·B)/B₀ (where L₀ and B₀ are characteristic length and magnetic field of the system, respectively). This study specifically targets Particle-In-Cell (PIC) simulations as a tool for design, where numerical effects are a concern for many devices using magnetically-confined plasmas, e.g. magnetic fusion machines, sputtering magnetrons, etc. A measure of numerically-induced heating and diffusion correlated to η would allow estimation of acceptable error in engineering design with limited computational resources.