  Planets are supposed to form in circumstellar disks. The gravitational
potential of a planet perturbs the disk and leads to characteristic structures,
i.e. spiral waves and gaps, in the disk's density profile. We perform a
large-scale parameter study of the observability of these planet-induced
structures in circumstellar disks with ALMA. On the basis of HD and MHD
simulations, we calculated the disk temperature structure and (sub)mm images of
these systems. These were used to derive simulated ALMA images. Because
appropriate objects are frequent in Taurus, we focused on a distance of 140pc
and a declination of 20{\deg}. The explored range of star-disk-planet
configurations consists of 6 HD simulations (including magnetic fields and
different planet masses), 9 disk sizes, 15 total disk masses, 6 different
central stars, and two different grain size distributions. On almost all scales
and in particular down to a scale of a few AU, ALMA is able to trace disk
structures induced by planet-disk interaction or by the influence of magnetic
fields on the wavelength range between 0.4 and 2.0mm. In most cases, the
optimum angular resolution is limited by the sensitivity. However, within the
range of typical masses of protoplanetary disks (0.1-0.001Msun) the disk mass
has a minor impact on the observability. It is possible to resolve disks down
to 2.67e-6Msun and trace gaps induced by a planet with M_p/M_s = 0.001 in disks
with 2.67e-4Msun with a signal-to-noise ratio greater than three. The central
star has a major impact on the observability of gaps, as well as the considered
maximum grainsize of the dust in the disk. In general, it is more likely to
trace planet-induced gaps in our MHD models, because gaps are wider in the
presence of magnetic fields. We also find that zonal flows resulting from MRI
create gap-like structures in the disk's re-emission radiation, which are
observable with ALMA.
