The linac-ring scenario is examined as a possible accelerator design
approach to electron-proton colliders, with center of mass energies between
14 GeV and 100 GeV and luminosity at the 10^33 level. Rf power and beam dump
considerations require that the electron linac recover the beam energy, a
technology demonstrated at Jefferson Lab's IR FEL. Parameters for two point
designs (5 GeV(e-) on 50 GeV(p) and 10 GeV(e-) on 250 GeV(p)) are shown. Accelerator
physics issues of the energy recovery electron linac, the proton ring, and
their interaction, are discussed. Luminosity projections based on fundamental
limitations are presented and a list of required R&D for the realization
of such a design is compiled.