  We report on the results of a simulation based study of colliding magnetized
plasma flows. Our set-up mimics pulsed power laboratory astrophysical
experiments but, with an appropriate frame change, are relevant to
astrophysical jets with internal velocity variations. We track the evolution of
the interaction region where the two flows collide. Cooling via radiative loses
are included in the calculation. We systematically vary plasma beta ($\beta_m$)
in the flows, the strength of the cooling ($\Lambda_0$) and the exponent
($\alpha$) of temperature-dependence of the cooling function. We find that for
strong magnetic fields a counter-propagating jet called a "spine" is driven by
pressure from shocked toroidal fields. The spines eventually become unstable
and break apart. We demonstrate how formation and evolution of the spines
depends on initial flow parameters and provide a simple analytic model that
captures the basic features of the flow.
