Top: contribution to Pedersen conductivity for each type of charge carrier. Bottom: ambipolar diffusion η_A according to Eq. (2) is shown with solid line, η_A under the assumption of overall constant ions mass m_i = 29m_p is shown with dotted line, and a frequently used η_A = B²/ (γρρ_i) is shown with dashed line. The asterix in ⟨ a ⟩ = 0.02 μm(^∗) indicates the mean dust radius is not a unique parameter to characterise the properties of dust and that model S5 has a maximal mean dust cross section.