Nonlinearity in a dynamo

Abstract

Using a rotating flat layer heated from below as an example, we consider effects which lead to stabilizing an exponentially growing magnetic field in magnetostrophic convection in transition from the kinematic dynamo to the full non-linear dynamo. We present estimates of the energy redistribution over the spectrum and helicity quenching by the magnetic field. We also study the alignment of the velocity and magnetic fields. These regimes are similar to those in planetary dynamo simulations.

Keywords:

• Boussinesq convection
• Geostrophy
• Quenching
• Triads

Notes

^†Large R _m is typical for many astrophysical bodies which possess their own magnetic field.