In order to reach the power density and total energy required for inertial confinement fusion targets using electron beams, a modular approach employing multiple diodes, plasma channel transport, and relativistic electron beam (REB) overlap is being pursued. This paper reports on an analytic study of the conversion efficiency of REB’s to ions by a combination of magnetic reflection and electrostatic reflexing of the electrons in the overlap region. The initial power density (but not total power) of the incident electron beam in this scheme is reduced by the ratio of electron beam overlap radius to final pellet radius squared, and the required power density gain in the overlap region is relaxed to unity. We find for a uniform REB energy distribution (the most probable distribution function at the overlap radius): (1) the ions cannot reach the full potential of the generator; (2) ion beam conversion efficiency remains low (∼5% in energy) and increases slowly with outer shell thickness; and (3) ion voltage remains almost constant for a wide range of generator voltages.