  We use 3D radiative MHD simulations to investigate the formation and dynamics
of small-scale (less than 0.5 Mm in diameter) vortex tubes spontaneously
generated by turbulent convection in quiet-Sun regions with initially weak mean
magnetic fields. The results show that the vortex tubes penetrate into the
chromosphere and substantially affect the structure and dynamics of the solar
atmosphere. The vortex tubes are mostly concentrated in intergranular lanes and
are characterized by strong (near sonic) downflows and swirling motions that
capture and twist magnetic field lines, forming magnetic flux tubes that expand
with height and which attain magnetic field strengths ranging from 200 G in the
chromosphere to more than 1 kG in the photosphere. We investigate in detail the
physical properties of these vortex tubes, including thermodynamic properties,
flow dynamics, and kinetic and current helicities, and conclude that magnetized
vortex tubes provide an important path for energy and momentum transfer from
the convection zone into the chromosphere.
