The role of magnetic fields during the initial stages of protostellar
cloud collapse
is investigated, in particular with respect to the scenario where the magnetic
force can be an effective compressor due to diamagnetic effects. A multifluid
approach involving electrons, ions of different atomic masses and neutrals
is
adopted, where each species is treated separately. The electron fluid is
compressed by the magnetic pressure force, and the other ion species are
pulled
by the collective electric field developed by the space charge separation.
The
neutrals are also dragged owing to collisions with the ions. The difference
in
charge-to-mass ratio ensures that each ion species is accelerated differently,
resulting in a distribution following their atomic masses. This model explores
the scenario where the electromagnetic forces can achieve a supercritical
mass-to-flux ratio in a magnetized cloud before dynamical collapse due
to gravity
takes over.