  A process of energy transfer is demonstrated in non-equilibrium charged
particle beams with anisotropy and space charge. Equipartitioning of energy
between available degrees of freedom occurs in just a few betatron wavelengths,
without halo formation. Collective space charge modes similar to those observed
in recent experiments provide the underlying coupling mechanism. Since
laboratory beams are commonly far from equilibrium, the traditional K-V
stability analysis does not necessarily apply, implying that selection of an
operating point based on theory does not necessarily avoid equipartitioning.
Furthermore, the rate of equipartitioning is shown to depend on a single free
parameter related space charge content of the final (equipartitioned) beam, and
does not depend on how the kinetic energy is initially distributed between the
two planes.
