Nonlinearity in a dynamo

TL;DR

This paper investigates the nonlinear effects in dynamo theory, focusing on how magnetic fields stabilize and energy redistributes in magnetostrophic convection, with implications for planetary dynamos.

Contribution

It provides new estimates of energy redistribution, helicity quenching, and field alignment in nonlinear dynamo regimes, bridging theoretical analysis and planetary simulation relevance.

Findings

Magnetic field stabilization in nonlinear dynamo regimes

Energy spectrum redistribution during dynamo transition

Alignment of velocity and magnetic fields in planetary-like conditions

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.