Intensification of Magnetic Fields by Conversion of Potential Energy

Abstract

A strong superequipartition magnetic field strength on the order of 10 T (105 G) has been inferred at the bottom of the solar convection zone. We show that the ``explosion'' of weak magnetic flux tubes, which is caused by a sudden loss of pressure equilibrium in the flux loop rising through the superadiabatically stratified convection zone, provides a mechanism that leads to a strong field: the flow of high-entropy material out of the exploded loop leads to a significant intensification of the magnetic field in the underlying flux sheet at the bottom. In contrast to the amplification by differential rotation, this process converts the potential energy of the stratification into magnetic energy and thus is not dynamically limited by the back-reaction on the flow field via the Lorentz force.