Kovalov I. Open resonant systems of diffraction radiation oscillators with developed interaction space

The goal of the research – experimentally and theoretically research ways to extend the functionality of diffraction radiation oscillator (DRO) with periodic structure in form of double comb, which operate in frequency range 20-300 GHz. Conduct research with promising open resonant systems with extended interaction space for the development of DRO in terahertz frequency range. The object of research – processes of resonant modes formation and processes of their interaction with electron beam in open resonant systems of DRO. Research methods - experimental research methods of resonant modes in open resonant systems taking into account radiation losses in a coupling node; results of linear theory of DRO with Gaussian field distribution along the interaction space; method of properties analysis of resonant modes using a 2-D model of open resonant system with an arbitrary profile of mirrors; experimental method of resonant field structure analysis directly on the mirror surface of an open resonant system using a movable coupling node; experimental method for determining ohmic losses in a periodic structure in form of double comb; experimental research methods of output parameters of DRO in “hot” operation mode. Novelty - The dependence of the resonant modes properties in ORS on the height of the double comb was investigated, and the optimal parameters of double comb were determined by criteria “wide frequency tuning range of DRO plus high quality factor of generated oscillations”. An experimental method is proposed for determining the field energy fraction of the resonant mode, concentrated directly in the grooves of the double comb, in relation to the energy of the resonant field in one variation of the constant wave of the ORS, and it is shown that it increases with increasing height of the double comb. For the first time, it was proposed and investigated the operation of the DRO on asymmetric modes that occur in the ORS when shifting the double comb to the periphery of the filed spot perpendicular to the electron flow, which reduced the destructive effect of the double comb on the operating mode, and allowed to increase the tuning range 1,5 times. For the first time, the peculiarities of the generator operation on coupled modes in an asymmetric ORS were studied, and the efficient operation of the DRO on one of the branches of the coupled modes in a wide frequency range without the influence of higher modes on the output characteristics of the generator was demonstrated. Degree of implementation - The results of the work can be used in the preparation and conduct of educational lectures in higher educational institutions of the Ministry of Education and Science of Ukraine, where the scientific fields of diffraction electronics and quasi-optics of open resonant systems are being investigated. Scope of use - The results obtained in the dissertation can be used in the development of packaged DRO with an extended frequency tuning range and the development of generators in the terahertz frequency range. The proposed method of analyzing the structure of the resonant field directly on the surface of the resonator mirror can be used in many practical applications of open resonators, such as dielectrometry, technological control of microwires etc.