Cherenkov free electron laser in an asymmetric dielectric liner waveguide

The small signal gain of a Cherenkov free electron laser is derived. The device consists of two different dielectric liner parallel plate waveguides driven by a cold relativistic electron beam. The results are compared with a standard Cherenkov free electron laser in a symmetric liner waveguide. It is observed that the asymmetric liner CFEL results agree well with the symmetric liner CFEL near the beam threshold but differ substantially at points far away from the beam threshold voltage.

► Theory for small signal gain in an asymmetric liner Cherenkov FEL i.e. ASCFEL has been analyzed.
► Use of ASCFEL modifies the dispersion curves with the cutoff frequency reduced to zero.
► Small signal gain of ASCFEL has been compared with the gain of SCFEL.
► Gains are similar at beam threshold while they differ significantly at a higher beam energy.