MEAN ELECTROMOTIVE-FORCE DUE TO MAGNETOCONVECTION IN A ROTATING HORIZONTAL LAYER WITH RIGID BOUNDARIES

The instability due to vertical temperature gradient is studied in a r apidly rotating horizontal layer of an electrically conducting fluid p ermeated by an azimuthal magnetic field, which linearly grows with dis tance from the vertical rotation axis. Both boundaries of the layer ar e rigid and perfectly thermally conductive. Various electrical conduct ivity combinations of the boundaries are considered together with the case of the Earth's core boundary conditions. The methods of Mean Fiel d MHD are used to compare electromotive force (EMF) in all investigate d cases of boundary conditions. The effect of electrical conductivitie s of boundaries on hydromagnetic instabilities and the EMF is not stro ng outside the boundary layers in the case of thermal modes. However, both the instabilities and the EMF in the whole layer are very sensiti ve to electromagnetic boundary conditions in the case of magnetically driven modes.