  We construct a two-parameter family of models for self-collimated, radially
self-similar magnetized outflows from accretion disks. A flow at zero initial
poloidal speed leaves the surface of a rotating disk and is accelerated and
redirected toward the pole by helical magnetic fields threading the disk. At
large distances from the disk, the flow streamlines asymptote to wrap around
the surfaces of nested cylinders. In constrast to previous disk wind modeling,
we have explicitly implemented the cylindrical asymptotic boundary condition to
examine the consequences for flow dynamics. The solutions are characterized by
the logarithmic gradient of the magnetic field strength and the ratios between
the footpoint radius R_0 and asymptotic radius R_1 of streamlines; the Alfven
radius must be found as an eigenvalue. Cylindrical solutions require the
magnetic field to drop less steeply than 1/R. We find that the asymptotic
poloidal speed on any streamline is typically just a few tenths of the Kepler
speed at the corresponding disk footpoint. The asymptotic toroidal Alfven speed
is, however, a few times the footpoint Kepler speed. We discuss the
implications of the models for interpretations of observed optical jets and
molecular outflows from young stellar systems. We suggest that the difficulty
of achieving strong collimation in vector velocity simultaneously with a final
speed comparable to the disk rotation rate argues against isolated jets and in
favor of models with broader winds.
