Diffusion processes in Ap-stars and white dwarfs

Diffusion processes in a completely ionized multicomponent plasma are studied. The transport phenomena for ions as well : as for electrons are considered. The transport coefficients are derived by two-polynomial Chapman-Enskog technique. The effect of the magnetic field on transport phenomena is taken into account. Detailed comparison of the obtained results with those of other authors is made. Some possible astrophysical consequences of the theory (surface layers of Ap-stars and white dwarfs) are briefly discussed in conclusion