  We show how an appropriate stationary crystalline structure of the magnetic
field can induce a partial fragmentation of the accretion disk, generating an
axial jet seed composed of hot plasma twisted in a funnel-like structure due to
the rotation of the system. The most important feature we outline is the high
degree of collimation, naturally following from the basic assumptions
underlying the crystalline structure. The presence of non-zero dissipative
effects allows the plasma ejection throughout the axial jet seed and the
predicted values of the accretion rate are in agreement with observations.
