Features of wave processes in pre-modulated electron beam and its interaction with electromagnetic field

Summary form only given. Wave processes in pre-modulated electron stream interacted with electromagnetic field has been considered in the framework of 2-dim linear theory. Influences of space charge (thin beam model [1]) and finite focusing magnetic field have been taken into account. For describing the interaction the system included excitation equation of rf electric field and equations of rf electron displacements has been used. Analysis [2] predicted the excitation of space charge waves and cyclotron waves and the resonance occurrence at synchronism of one of them with wave in transmission line. In some cases space charge leads to instability appearance. Two types of instability in strip and tubular electron streams have been defined: spatial static and rf instability. Special attention is given to the rf instability, occurring in the interaction with e/m fields. Its condition has been derived taking into account the effects of both the space charge and magnetic fields, and it is pointed at possibility of some improvement of interaction efficiency. Electron flow pre-modulation is possible especially due to using of photo-cathodes and cold cathodes that could be applied in THz devices because of their peculiarities. By setting initial conditions in different ways the effect of magnetic field on interaction has been investigated in photo-TWT, carcinotrode (BWO with emission automodulation [3]), BWO in pre-generation regime, also its influence on behavior of noise factor in TWT has been considered. Successive approximation and dispersion equation methods have been applied for solving. The resonances allow to investigate two-waves approaching, in which start-up conditions of carcinotrode (synchronic regime, earlier unexplored cyclotron resonance regime) have been derived. The conformity of results in general case and in two-waves approaching is shown.