Abstract
The unified Dynamo-Reverse Dynamo (Dy-RDy) mechanism, capable of
simultaneously generating large scale outflows and magnetic fields from an
ambient microscopic reservoir, is explored in a broad astrophysical context.
The Dy-RDy mechanism is derived via Hall magnetohydrodynamics, which unifies
the evolution of magnetic field and fluid vorticity. It also introduces an
intrinsic length scale, the ion skin depth, allowing for the proper
normalization and categorization of microscopic and macroscopic scales. The
large scale Alfvén Mach number \$M\_A\$, defining the relative
äbundance" of the flow field to the magnetic field is shown to be tied to a
microscopic scale length that reflects the characteristics of the ambient short
scale reservoir. The dynamo (Dy), preferentially producing the large scale
magnetic field, is the dominant mode when the ambient turbulence is mostly
kinetic, while the outflow producing reverse dynamo (RDy) is the principal
manifestation of a magnetically dominated turbulent reservoir. It is
conjectured that an efficient RDy may be the source of many observed
astrophysical outflows that have \$M\_A 1\$.
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