  Relativistic current carrying strings moving axisymmetrically on the
background of a Kerr black hole are studied. The boundaries and possible types
of motion of a string with a given energy and current are found. Regions of
parameters for which the string falls into the black hole, or is trapped in a
toroidal volume, or can escape to infinity, are identified, and representative
trajectories are examined by numerical integration, illustrating various
interesting behaviors. In particular, we find that a string can start out at
rest near the equatorial plane and, after bouncing around, be ejected out along
the axis, some of its internal (elastic or rotational kinetic) energy having
been transformed into translational kinetic energy. The resulting velocity can
be an order unity fraction of the speed of light. This process results from the
presence of an outer tension barrier and an inner angular momentum barrier that
are deformed by the gravitational field. We speculatively discuss the possible
astrophysical significance of this mechanism as a means of launching a
collimated jet of MHD plasma flux tubes along the spin axis of a gravitating
system fed by an accretion disk.
