  An investigation on the mechanism of relaxation of axially confined 400 GeV/c
protons to planar channeling in a bent crystal was carried out at the extracted
line H8 from CERN Super Proton Synchrotron. The experimental results were
critically compared to computer simulations, showing a good agreement. We
firmly individuated a necessary condition for the exploitation of axial
confinement or its relaxation for particle beam manipulation in high-energy
accelerators. We demonstrated that with a short bent crystal, aligned with one
of its main axis to the beam direction, it is possible to realize either a
total beam steerer or a beam splitter with adjustable intensity. In particular,
in the latter case, a complete relaxation from axial confinement to planar
channeling takes place, resulting in beam splitting into the two strongest skew
planar channels.
