  Astrophysical accretion is arguably the most prevalent physical process in
the Universe; it occurs during the birth and death of individual stars and
plays a pivotal role in the evolution of entire galaxies. Accretion onto a
black hole, in particular, is also the most efficient mechanism known in
nature, converting up to 40% of accreting rest mass energy into spectacular
forms such as high-energy (X-ray and gamma-ray) emission and relativistic jets.
Whilst magnetic fields are thought to be ultimately responsible for these
phenomena, our understanding of the microphysics of MHD turbulence in accretion
flows as well as large-scale MHD outflows remains far from complete. We present
a new theoretical model for astrophysical disk accretion which considers
enhanced vertical transport of momentum and energy by MHD winds and jets, as
well as transport resulting from MHD turbulence. We also describe new global,
3D simulations that we are currently developing to investigate the extent to
which non-ideal MHD effects may explain how small-scale, turbulent fields
(generated by the magnetorotational instability -- MRI) might evolve into
large-scale, ordered fields that produce a magnetized corona and/or jets where
the highest energy phenomena necessarily originate.
