  We carried out a parameter study of interacting disk galaxies with impact
parameters ranging from central collisions to weakly interacting scenarios. The
orientations of the disks were also varied. In particular, we investigated how
magnetic field amplification depends on these parameters. We used
magnetohydrodynamics for gas disks in combination with live dark-matter halos
in adaptive mesh refinement simulations. The disks were initialized using a
setup for isolated disks in hydrostatic equilibrium. Small-scale filtering of
the velocity and magnetic field allowed us to estimate the turbulent
electromotive force (EMF) and kinetic helicity. Time series of the average
magnetic field in central and outer disk regions show pronounced peaks during
close encounters and mergers. This agrees with observed magnetic fields at
different interaction stages. The central field strength exceeds 10 microgauss
(corresponding to an amplification factor of 2 to 3) for small impact
parameters. As the disks are increasingly disrupted and turbulence is produced
by tidal forces, the small-scale EMF reaches a significant fraction of the
total EMF. The small-scale kinetic helicity is initially antisymmetric across
the disk plane. Though its evolution is sensitive to both the impact parameter
and inclinations of the rotation axes with respect to the relative motion of
the disks, antisymmetry is generally broken through interactions and the merger
remnant loses most of the initial helicity. The EMF and the magnetic field also
decay rapidly after coalescence. The strong amplification during close
encounters of the interacting galaxies is mostly driven by helical flows and a
mean-field dynamo. The small-scale dynamo contributes significantly in
post-interaction phases. However, the amplification of the magnetic field
cannot be sustained.
