Plasma-filled dielectric Cherenkov maser

The effect of a background plasma on a dielectric Cherenkov maser is examined by solving the linearized, beam-plasma, dielectric-lined waveguide dispersion relation. The results indicate that introduction of the background plasma can produce a higher spatial growth rate for the beam-waveguide instability and can reduce the electric field at the dielectric surface when compared to the system with no background plasma present. It is also found that for some sets of waveguide parameters, the TM_0n electromagnetic modes can propagate frequencies that are below the background plasma frequency in the system. These modes have a finite off frequency and are different from the Trivelpiece-Gould modes for the system