Two-stream Smith–Purcell free-electron laser

An analysis of two-stream Smith–Purcell (SP) free-electron laser (FEL) is presented in this paper. A rectangular grating is considered to be driven by two admixed electron beams with velocity separation. The dispersion equation is derived with the help of linearized fluid theory, and the beam–wave interaction is analyzed through the numerical computation. The enhancement of growth rate due to the two-stream instability has been demonstrated, as well as the frequency characteristics are reported.