Characteristics of the dispersive free-electron laser

The dispersive free-electron laser (DFEL) was previously introduced as an optical klystron (OK) superimposed upon a free-electron laser (FEL). In this paper it is shown that with proper design this device provides a gain increase of the order of 4 over the gain of the OK (for equal lengths) with a gain-energy acceptance product approaching that of the FEL. Even when the transverse excursion of the electron beam exceeds the optical beam dimension, there is only a slight reduction in gain from the above value.