Nonlinear characteristics of a cylindrical Cherenkov laser at millimeter wavelengths

Nonlinear characteristics of a cylindrical Cherenkov laser, which is composed of a dielectric-loaded coaxial waveguide and a hollow relativistic electron beam, are investigated with the use of particle simulation. The results obtained in this paper are compared with those for parallel plate and rectangular models. Numerical results show that, in the cylindrical Cherenkov laser, the electromagnetic (EM) wave grows exponentially in the longitudinal direction and reaches saturation, as is the case with the parallel plate and rectangular models. However, the efficiency of energy transfer from the electron beam to the EM wave in the cylindrical model is not in good agreement with that for the parallel plate model, especially for the case of a small radius of the inner conductor. Thus, we propose a modified parallel plate model whose growth characteristics are the same as those for the cylindrical model. With the use of the corresponding modified parallel plate model, one can calculate growth characteristics for the cylindrical model at a particular frequency more easily