  We show that if the turbulent magnetic diffusivity used in solar dynamos is
assumed to be 'quenched' by increasing toroidal fields, much larger amplitude
and more concentrated toroidal fields can be induced by differential rotation
from an assumed poloidal field than if there is no quenching. This
amplification and concentration mechanism is weakened and bounded by j x B
feedbacks on the differential rotation. Nevertheless, it is strong enough to
contribute to the creation of ~100 kG toroidal fields near the base of the
convection zone, perhaps in conjunction with the 'exploding flux tube' process.
Such high fields are necessary for sunspots to occur in low solar latitudes.
