Influence of magnetic fields on pulsed, radiative jets

We present results of magnetohydrodynamic simulations of steady and time va riable jets for a set of conditions applicable to outflows from young stell ar objects (YSOs). As a first step in a detailed study of radiative magneto hydrodynamic jets, we study both steady and pulsed jets with a large-scale magnetic field oriented parallel to the jet flow axis. While toroidal compo nents may be present in many jets, we have chosen in this initial study to focus solely on pure poloidal initial geometries. The range of magnetic fie ld strengths studied is characterized by the dimensionless parameter beta = 8 pi P-gas/B-2 = 0.1-10(7). The results of our simulations show that the g lobal characteristics are not strongly dependent on the strength of the mag netic field. Instead, we find that a predominantly poloidal field has more subtle effects, such as inhibiting instabilities, and increasing the "order " in the flow patterns. While the fields act to restrict "turbulent" gas mo tions, the pulse-induced internal shocks increase the likelihood of instabi lities, complicate the global flow patterns, and increase the likelihood of magnetic reconnection. We detail the ways in which the magnetic pressure a nd tension forces affect the kinematics observed in these simulations.