We consider the effect that a finitely conducting inner core may have on the dynamo
processes in the outer core. Because a finitely conducting inner core has a diffusive
timescale of its own of a few thousand years, which is long compared with the most rapid
advective timescales possible in the outer core, the field in the inner core must necessarily
average over these very rapid timescales. This averaging-out may then have a stabilizing
influence, preventing the very rapid timescales from dominating the dynamo processes in …