  An inhomogeneous transport current, which is introduced through multiple
electrodes in an open Nb microtube, is shown to lead to a controllable
branching of the vortex nucleation period. The detailed mechanism of this
branching is analyzed using the time-dependent Ginzburg-Landau equation. The
relative change of the vortex nucleation period strongly depends on the
geometry of multiple electrodes. The average number of vortices occurring in
the tube in a nanosecond can be effectively reduced owing to the inhomogeneous
transport current, what is important for noise and energy dissipation reduction
in superconductor applications, e.g., for an extension of the operation regime
of superconductor-based sensors to lower frequencies.
