The Biermann battery effect at the interfaces in stratified plasmas

The Biermann battery arises because an inhomogeneous electron pressure acts as a source term for the magnetic field. In order to better understand its effects, we consider a simplified model formed by the boundary between two fluids with different mean molecular weight and look for magnetic fields generated by the battery and localized in a band around the interface. We show that a parallel field is generated, which tends to push the original flow away from the boundary creating a rarefaction band. The specific forms of magnetic field and velocity are detailed.