Likhachov O. Spectral characteristics and stability of clinotron radiation in the millimeter and submillimeter ranges taking into account the features of energy exchange processes

The purpose of the work is to study the influence of the longitudinal velocities of electrons distribution in dense ribbon beams, which arises due to the presence of the accelerating voltage ripples, on the efficiency of beam-wave interaction in clinotrons oversized electrodynamic systems in millimeter and submillimeter ranges and on the radiation spectral characteristics for the frequency modulation modes implementation according to linear and by power rules. The object of research is the processes of formation and transportation of dense ribbon electron beams in a weakly inhomogeneous magnetic field, as well as the processes of beam-wave interaction in electrodynamic systems of clinotrons. Theoretical and practical results. The level accelerating voltage ripples of the was established, which does not distort the distribution of electron velocities, which is formed in the diode gun of the clinotron in the presence of a static magnetic field. Experimental results of continuous clinotrons in the frequency range of 200–400 GHz showed that the beam voltage stability of 10-5 provides a spectral linewidth of about 1 MHz. A spectral linewidth of 1.18 MHz was demonstrated for a continuous 310 GHz to 360 GHz frequency range clinotron at an operating frequency of 346.4 GHz with an output power of 100 mW when the output voltage stability of the high voltage power supply was 5x10-6. Novelty of scientific results. For the first time, the radiation spectral linewidth dependence on the resonance properties of the clinotrons electrodynamic system was obtained. Based on the obtained theoretical and experimental data, frequency modulation was implemented according to the rules of linear frequency modulation within one generation zone of clinotrons in millimeter and submillimeter ranges, and using a step frequency mode with transition between separated zones of generation in the clinotron in millimeter range. Research methods. Numerical solution of the Poisson equation and the motion of charged particles by the fourth-order Runge-Kutta method, self-consistent solution of the wave excitation equation and electron flow motion equation by the finite difference method. The experimental part was carried out according to the classical methods of measuring power and frequency for the terahertz range. Degree of implementation. The results of the work can be used in the creation of THz visualization systems with frequency modulation and with a constant frequency. Scope of use. Developed in the dissertation power system for clinotrons with additional PID stabilization circuits and the possibility of frequency modulation, can be used as a source of electromagnetic radiation in three-dimensional visualization tasks.