Effects of axial magnetic field strength on radiation efficiency of plasma-beam superheterodyne free electron laser of dopplertron type

We have obtained the system of cubic-nonlinear differential equations for the complex amplitudes of the electromagnetic fields of eigenwaves in a plasma-beam superheterodyne free-electron laser (FEL) of the Doppleron type. We have found that a decrease of the axial guiding magnetic field strength leads to an increase of the signal wave saturation levels. We have found the value of the axial guiding magnetic field strength at which a maximal amplitude electromagnetic radiation in the millimeter wavelength range is formed.