  Energy recovery linacs have been studied and developed over a number of
decades. In the standard arrangement there is a separate particle source and
particle beam dump. In this paper, a new arrangement is explored where the
energy recovery linac is used as an energy source in a storage ring which has
multiple beam energies. Several interesting topologies for the multiple beam
energies are shown schematically. Possible energy equilibria with and without
radiation damping are discussed. This idea may have applications to the problem
of electron cooling.
