Convection driven dynamos

Various models of thermal convection in rapidly rotating fluids permeated by strong magnetic fields are discussed. Particular attention is paid to the possibility that the magnetic field can be maintained by dynamo action rather than by externally applied electric currents. Two dynamo models are given particular attention. They are the plane layer model of Childress and Soward (1972) and the annulus model of Busse (1975). Though these models do not totally resolve the geodynamo problem, they do highlight important features of hydromagnetic dynamos. As a result some speculations are made about the true character of the geodynamo.