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tokens: component is induced. As a result, a weaker toroidal field pressure is available for the disk wind ejection and acceleration. In this sense, the increasing magnetic diffusivity also suppresses the ejection process in the system. 7.2. Efficiency of Outflow Launching We have discussed above the influence of magnetic diffusivity on the ejection process. In general, magnetic diffusivity lowers the ejection rate. However, we have noticed that the magnetic diffusivity may lead to a higher outflow efficiency . Here we define the outflow efficiency aswhere and are the total ejection rate and the inner accretion rate, respectively, defined in Section 3.5 . We note that outflow efficiencies ξ > 1 are possible. In Table 2 we show the outflow efficiency ξ for the different simulations averaged from t = 2000 to t = 3000. In general, the outflow efficiency of disks with η 0 > 10 −4 is much larger than that of weakly diffusive disks with η 0 10 −4 . At this stage we may only speculate about the reason for this trend. One possibility may be the field structure just above the disk. The region above the accretion disk evolves as in ideal MHD. Material is frozen to the field lines and either flows along the field or needs to “push” the magnetic field component that is perpendicular to the motion. We find that the simulations with lower disk magnetic diffusivity result in a more tangled field structure (as discussed above, most probably due to the not fully stable initial disk hydrodynamics). One may argue that the tangled field is advected upward along with the outflow and then lowers the efficiency of acceleration. Also, mass loading is known to be governed by the physical conditions at the disk surface or the sonic surface. In our case of a super-Alfvénic injection, Lorentz forces will play a major role. We conjecture that for a tangled magnetic field the Lorentz forces are also tangled and thus less efficient in launching. In Figure 16 we show the field-line structures for simulations D 1 (left panel) and D 10 (right panel) at t = 2000. In the nondiffusive simulation D 1 (outflow efficiency ξ = 0.5), the matter flow inside the disk becomes turbulent, also disturbing the smooth structure of field lines. The disturbance propagates outward, leading to a field structure that is suppressing efficient acceleration. On the other hand, the field lines in simulation D 10 (outflow efficiency ξ = 2.9) still keep their original smooth structure at t = 2000. Figure 16. Density and magnetic field line distribution (zoomed in) for simulations D 1 (left) and D 10 (right) at t = 2000. In simulation D 1 the field lines inside the disk have a more turbulent distribution (especially within r 20), most probably due to the MRI. Another possibility for the observed interrelation between diffusivity and mass loading can be ohmic heating. This will result in a somewhat higher sound speed at the disk surface for the more diffusive disk. From steady-state MHD wind theory and