The properties of an intense annular relativistic electron beam generated by a ring cathode and conical anode have been studied in detail. The beam is injected into a channel between concentric cones (containing a neutral gas for space charge and current neutralization) where it is transported and focused. Half of the return current is then fed back through the cathode to prevent radial pinching of the primary current sheet. On the Sandia Reba accelerator which generated a beam of about 120 kA at 1 MeV an area compression of 10 was achieved with 50% efficiency. The compressability of the beam was found to depend primarily on the azimuthal temperature of the beam as it emerged from the diode and on the diode plasma closure rate.