  We report on flux confinement effects in superconducting submicron line, loop
and dot structures. The main idea of our study was to vary the boundary
conditions for confinement of the superconducting condensate by taking samples
of different topology and, through that, modifying the lowest Landau level
E_{LLL}(H). Since the critical temperature versus applied magnetic field
T_{c}(H) is, in fact, E_{LLL}(H) measured in temperature units, it is varied as
well when the sample topology is changed. We demonstrate that in all studied
submicron structures the shape of the T_{c}(H) phase boundary is determined by
the confinement topology in a unique way.
