A SIMPLE TYPE OF MAGNETICALLY DRIVEN JETS - AN ASTROPHYSICAL PLASMA GUN

We propose a simple theoretical formulation of the problem of magnetic ally driven outflows when poloidal magnetic flux surfaces are absent, and the magnetic field has only a toroidal component. The present form ulation is the limiting case of the more general Grad-Shafranov one, w hen B-p/B-phi --> 0. We show that the toroidal magnetic field alone is very efficient in accelerating and collimating outflows (jets) from a ccretion disks. We therefore suggest that the important physical mecha nism which might be responsible for jet production in the inner part o f a fully ionized thick accretion disk around an active galactic nucle us is the buildup of the toroidal magnetic field component by the diff erential rotation of the disk, and its subsequent escape out of the di sk. This is qualitatively different from the centrifugal driving mecha nism of Blandford and Payne (1982), which might be important only in t he partially ionized parts of the accretion disk where B-p similar to B-phi. Our formalism is also applied to describe briefly the time-depe ndent problem.