Forming of Ultrashort Electromagnetic Clusters by Two-Stream Superheterodyne Free Electron Lasers

We construct a cubic nonlinear self-consistent theory of multiharmonic two-stream superheterodyne free electron lasers of a klystron type, intended to form powerful ultrashort clusters of an electromagnetic field. Plural three-wave parametric resonant interactions of wave harmonics have been taken into account. The two-stream superheterodyne free electron lasers mode in which the first harmonic of a space-charge wave is much smaller than the critical frequency of two-stream instability has been used for forming of the powerful ultrashort clusters of electromagnetic waves. We carry out amplitude, phase and spectral analyses of the processes occurring in such devices. We found out the conditions necessary for the forming of the ultrashort clusters of an electromagnetic field. We demonstrate the possibility of the ultrashort electromagnetic cluster formation in the multiharmonic two-stream superheterodyne free electron lasers-type systems.