The role of initial magnetic field structure in the launching of
  protostellar jets
  Magnetic fields are known to play a crucial role in the star formation
process, particularly in the formation of jets and outflows from protostellar
discs. The magnetic field structure in star forming regions is not always
uniform and ordered, often containing regions of magnetic turbulence. We
present grid-based, magneto-hydrodynamical simulations of the collapse of a
1$\,\mathrm{M}_{\odot}$ cloud core, to investigate the influence of complex
magnetic field structures on outflow formation, morphology and efficiency. We
compare three cases: a uniform field, a partially turbulent field and a fully
turbulent field, with the same magnetic energy in all three cases. We find that
collimated jets are produced in the uniform-field case, driven by a
magneto-centrifugal mechanism. Outflows also form in the partially turbulent
case, although weaker and less collimated, with an asymmetric morphology. The
outflows launched from the partially turbulent case carry the same amount of
mass as the uniform-field case but at lower speeds, having only have 71$\%$ of
the momentum of the uniform-field case. In the case of a fully turbulent field,
we find no significant outflows at all. Moreover, the turbulent magnetic field
initially reduces the accretion rate and later induces fragmentation of the
disc, forming multiple protostars. We conclude that a uniform poloidal
component of the magnetic field is necessary for the driving of jets.
