  Large-scale magnetic fields in galaxies are thought to be generated by a
turbulent dynamo. However the same turbulence also leads to a small-scale
dynamo which generates magnetic noise at a more rapid rate. The efficiency of
the large-scale dynamo depends on how this noise saturates. We examine this
issue taking into account ambipolar drift, which obtains in a galaxy with
significant neutral gas. We argue that, (1) the small-scale dynamo generated
field does not fill the volume, but is concentrated into intermittent rope like
structures. The flux ropes are curved on the turbulent eddy scales. Their
thickness is set by the diffusive scale determined by the effective ambipolar
diffusion; (2) For a largely neutral galactic gas, the small-scale dynamo
saturates, due to inefficient random stretching, when the peak field in a flux
rope has grown to a few times the equipartition value; (3) The average energy
density in the saturated small-scale field is sub equipartition, since it does
not fill the volume; (4) Such fields neither drain significant energy from the
turbulence nor convert eddy motion of the turbulence on the outer scale into
wavelike motion. The diffusive effects needed for the large-scale dynamo
operation are then preserved until the large-scale field itself grows to near
equipartition levels.
