  The upper critical field in type II superconductors is limited by the Pauli
paramagnetic limit. In superconductors with strong Rashba spin-orbit coupling
this limit can be overcome by forming a helical state. Here we quantitatively
study the magnetic field-temperature phase diagram of finite-size
superconductors with Rashba spin-orbit coupling. We discuss the effect of
finite size and shape anisotropy. We demonstrate that the critical field is
controllable by intrinsic parameters such as spin-orbit coupling strength and
tunable parameters such as sample geometry and applied field direction. Our
study opens new avenues for the design of superconducting spin-valves.
