Rikitake dynamo

[Beer-monster]

Could someone please explain to me (qualitively as well as quantitively) the physical concepts and theory behind a Rikitake two-disk dynamo and its effects. Or if you could point me to somewhere that does so in terms a semi-layman (i.e an undergraduate who prefers things put as simple as possible and without technical words in order to get a general gist :biggrin: ) can understand.

Any help will be greatly appreciated