Space-charge Wave Theory Of Free Electron Lasers

The linear theory of free electron lasers (FELs) is provided from the point of view of space-charge waves. The basic equation describing the space-charge waves in FELs is derived and analyzed. A new kind of hybrid free electron laser with a slow-wave circuit, which may enhance efficiency with the aid of coupling of the first space harmonic with the space-charge wave, is presented.