  The shape and the dynamics of reversals of the magnetic field in a turbulent
dynamo experiment are investigated. We report the evolution of the dipolar and
the quadrupolar parts of the magnetic field in the VKS experiment, and show
that the experimental results are in good agreement with the predictions of a
recent model of reversals: when the dipole reverses, part of the magnetic
energy is transferred to the quadrupole, reversals begin with a slow decay of
the dipole and are followed by a fast recovery, together with an overshoot of
the dipole. Random reversals are observed at the borderline between stationary
and oscillatory dynamos.
