Flux from a homogeneous slab summed over the two polarization modes for the higher (left) and lower (right) electron number densities, for B ≈ 5.2 × 10¹² G. Different types of polarization modes are shown: pure-plasma (“pl”, dotted), pure-vacuum (“v”, thick dashes) modes, and modes with continuous and discontinuous (“pl+v: cri” and “pl+v: dri”, dashed and solid, respectively) refractive indices.