  The generation of astrophysically relevant jets, from magnetically
collimated, laser-produced plasmas, is investigated through three-dimensional,
magneto-hydrodynamic simulations. We show that for laser intensities I ~ 10^12
- 10^14 W/cm^2, a magnetic field in excess of ~ 0.1 MG, can collimate the
plasma plume into a prolate cavity bounded by a shock envelope with a standing
conical shock at its tip, which re-collimates the flow into a super
magneto-sonic jet beam. This mechanism is equivalent to astrophysical models of
hydrodynamic inertial collimation, where an isotropic wind is focused into a
jet by a confining circumstellar torus-like envelope. The results suggest an
alternative mechanism for a large-scale magnetic field to produce jets from
wide-angle winds. (abridged version)
