  We analyze diffusion equations in strongly coupled Coulomb mixtures of ions
in dense stellar matter. Strong coupling of ions in the presence of
gravitational forces and electric fields (induced by plasma polarization in the
presence of gravity) produces a specific diffusion current which can separate
ions with the same A/Z (mass to charge number) ratios but different Z. This
Coulomb separation of ions can be important for the evolution of white dwarfs
and neutron stars.
