Kinematic dynamos in precession-driven cavities

Kinematic dynamos in precession-driven ca vities S. V an tie ghem * and A. Jackson ETH Zuric h It has recently been argued that precession may pro vid e an alternativ e energy source for the natural dynamos of planets and moons. Using a finite-volume code, w e pursue a numerical investigation of precession-driven kinematic dynamos in whole spheroids and spheroidal shells. W e find that laminar precession can power a dynamo and that the critical magnetic Reynolds number for the onset of dynamo action is lower if an inner core is presen t. Finally, we also discuss the spatial structure of the magnetic field.