Push-Pull FEL, a new ERL concept

This proposal uses two sets of superconducting cavities with two identical electron beams going in opposite directions. Each set of superconducting cavities accelerates one electron beam and decelerates the other beam. This arrangement allows the energy used to accelerate one beam to be recovered and used again for the other beam. The difference between this proposal and other energy-recovery proposals is that each electron beam is decelerated by a different structure than that which accelerated it so this is energy exchange rather than energy recovery.If the superconducting cavities produce sufficient energy, a further simplification can occur. In this arrangement, the superconducting cavities are contained within the optical resonator with the light pulses traversing them. This arrangement leads to an extremely compact layout suitable for a university laboratory.