Laser assisted electron beam conditioning for free electron lasers

A new method for electron beam conditioning in free electron lasers is proposed. It uses the electron beam interaction with a laser light in two wiggler magnets separated by a strong-focusing channel. The effect of the conditioning is illustrated by the example of a hypothetical single-pass, high-gain free electron laser operating in the self-amplified spontaneous emission mode with the x-ray emission at lambda(x) = 1.5 angstrom. The proposed conditioner is relatively compact and can be used as a practical add-on device to short x-ray wavelength free electron lasers.