A homopolar generator, is a DC electrical generator in which the magnetic field has the same polarity at every point, so that the armature passes through the magnetic field lines of force continually in the same direction.
A homopolar generator, is a DC electrical generator in which a rotating disk has a magnetic field passing thru it. It has the same polarity at every point, so that the armature passes through the magnetic field lines of force continually in the same direction.