I.A. Nakrap – Ph.D.(Phys.-Math.), Associate Professor, 

Department of Radiotechnique and Electrodynamics, Saratov State University named after N.G. Chernyshevsky E-mail: nakrapia@info.sgu.ru

A.N. Savin – Ph.D.(Phys.-Math.), Leading Research Scientist, 

JSC «RPC «Istok» named after Shokin» (Fryazino)

E-mail: savinan01@yandex.ru

Simulation of TWT on the CCC in the conditions of confluence modes stands an actual and important task of studying the conditions and causes of possible instability of TWT near and at the point of the merger of cavity and slot passbands of the CCC. The purpose of this work is experimental study of bandpass characteristics (VSWR and transfer coefficient) CCC with power ports, as well as their longitudinal field distributions of on resonant modes of passbands. At the investigation are used optimized for electrodynamic characteristics (EDC) of CCC with combined bands with a smooth change in their dispersion characteristics and the final value of the coupling impedance in the merging region. At the same time, the characteristics of the transmission coefficient and the field distribution of SWS showed the presence in this area of the stop band of small width (less than 2%) with a small attenuation, as well as the excitation of local oscillations in it. Incomplete merging of bands and especially excitation of local oscillation in this area can be the conditions of possible instability of TWT of coalesced modes. Moreover, the increase in the discontinuity of the periodic structure (nonidentical of the end cells in comparison with the resonators of the CCC regular part) should lead not only to the expansion of the stop band between the modes, but also to a significant increase in the amplitude of local oscillations in it. Thus, in the simulation (calculation and optimization) TWT with the combined modes, you need to determine with greater precision EDC CCC, especially in the region of steep dispersion near the edge passband of the SWS in the process of their merger. The study of the dynamics of the merger of bands CCC should be carried out in determining the boundaries of not only the resonator, but also the slot passbands to the complete disappearance of the stop band between them.

1. Carter Richard G. Microwave and RF Vacuum Electronic Power Sources. Cambridge University Press. 2018. Lancaster University. ISBN 978-0-521-19862-2.
2. Sauseng O., Triplett M.E. A 5 kW wideband coupled cavity tube with ppm focusing for 11 GHz to 17 GHz. IDEM. Washington. 1974. P. 491−493. DOI: 10.1109/IEDM.1974.6219800.
3. Karp A., Ayers W.R. Design concepts for an octave-band width coupled-cavity TWT. IDEM. Washington. 1978. P. 546−549. DOI: 10.1109/IEDM.1978.189475.
4. Liu, Shunkang. Expanding to the bandwidth of the coupled cavity TWTs in MMW. International Journal of Infrared and Millimeter Waves. 2001. V. 22. № 2. P. 309−314. DOI:10.1023/A:1010700421777.
5. James B.G. et al. New Circuit for Generating High Power at Millimeter Wavelengths. MOGA 70. Amsterdam. Holland. P. 5.7−5.13.
6. Nej S., Christie L. Coupled resonator slow wave structures for millimetric wave TWT. International Conference on Energy, Communication, Data Analytics and Soft Computing (ICECDS 2017). Chennai (India). 19 June 2018. P. 1209−1211. DOI: 10.1109/ICECDS.2017.8389634.
7. Nakrap I.A., Savin A.N., Orudzhev A.B., Shindyapina N.B. Issledovanie dinamiki sblizheniya rezonatornoi i shchelevoi polos propuskaniya zamedlyayushchei sistemy tipa TsSR. Tezisy dokladov Mezhdunar. nauchno-tekhnich. konf. «Aktualnye problemy elektronnogo priborostroeniya» (APEP-94). 4−7 oktyabrya 1994 g. Saratov: Izd-vo SGTU. 1994. S. 65. ISBN 5-7433-0057-7.
8. Savin A.N. Issledovanie elektrodinamicheskikh kharakteristik struktur vakuumnoi elektroniki i magnitoelektroniki SVCh na osnove regressionnykh modelei: Diss. … kand. fiz.-mat. nauk. Saratov: SGU. 2003.
9. Savin A.N., Nakrap I.A., Doronin D.M. The equivalent circuit parameters calculation of a coupled cavity chain using electrodynamic characteristics. Conference Proceedings of 20-th International Crimean Conference Microwave and Telecommunication Technology (CriMiCo'2010). 5632593. P. 253−254. ISBN 978-966-335-333-3.
10. Nakrap I.A., Savin A.N. Elektrodinamicheskie kharakteristiki TsSR s obrashchennoi shchelevoi modoi. Materialy 27-oi Mezhdunar. Krymskoi konf. «SVCh-tekhnika i telekommunikatsionnye tekhnologii» (KryMiKo-2017). 10−16 sentyabrya 2017. Sevastopol (Rossiya). T. 1. S. 199−207. ISBN: 978-966-335-434-7.
11. Horsley A.W., Pearson A. Measurement of dispersion and interaction impedance characteristics of slow-wave structures by resonance methods. IEEE Trans. Electron Devices. 1966. V. ED-13. P. 962−969. DOI: 10.1109/T-ED.1966.15876.
12. Savin A.N., Nakrap I.A., Vakhlaeva C.P., Kornyakov V.V. The automation of a resonant perturbation method to research electrodynamic characteristics of microwave devices. Proceedings of the 2015 International Conference on Testing and Measurement: Techniques and Applications (TMTA-2015). 2015. P. 7−9. ISBN: 978-1-138-02812-8.
13. Steele C.W. A Nonresonant Perturbation Theory. IEEE Transactions on Microwave Theory and Techniques (MTT-14(2). 1966. P. 70−74. DOI: 10.1109/TMTT.1966.1126168.
14. Pavlovskii V.A. Opredelenie koeffitsienta otrazheniya i raspredeleniya elektricheskogo polya po dline kruglogo diafragmirovannogo volnovoda KDV. V sb. Uskoriteli. № 13. M.: Atomizdat. 1974.
15. Nakrap I.A., Nasedkin A.A., Kharchenko V.V., Shindyapina N.B. Issledovanie soglasovaniya i raspredeleniya polya neodnorodnykh tsepochek svyazannykh rezonatorov. Elektronnaya tekhnika. Ser. 1. Elektronika SVCh. 1985. № 3.
16. Fano R.M. Teoreticheskie ogranicheniya polosy soglasovaniya proizvolnykh impedansov: Per. s angl. Yu.L. Khotuntseva. Pod red. T.I. Slobodenyuka. M.: Sov. radio. 1965.
17. Nakrap I.A., Savin A.N. Localized fields in stopbands of the coupled nonidentical cavity chain. 17-th International Crimean Conference (CriMiCo-2007) «Microwave and Telecommunication Technology». 2007. 4368662. P. 141−142. ISBN 978-966-335-015-8.
18. Nakrap I.A., Savin A.N. Local oscillations in the limited periodic structure such as a coupled cavity chain. Conference Proceedings International Conference on Actual Problems of Electrons Devices Engineering (APEDE-2006). 4099640. P. 287−295. ISBN 5-7433-1701-1.
19. Nakrap I.A., Savin A.N., Sharaevsky Yu.P. The influence of dipole effect of evanescent waves on field distribution in slow wave structure such as coupled cavity chain with phase velocity jump of the wave. Conference Proceedings of 15-th International Crimean Conference «Microwave and Telecommunication Technology» (CriMiC-2005). 2005. 1564874. P. 209−210.
20. Nakrap I.A., Savin A.N., Sharaevsky Yu.P. Forsed and own waves of coupled cavity periodic structure. Conference Proceedings of 4-th International Crimean Conference «Microwave and Telecommunication Technology» (CriMiC-2004). 2004. P. 197−198. ISBN 966-7968-69-3.
21. Nakrap I.A., Savin A.N. Elektrodinamicheskie kharakteristiki mnogoryadnoi vstrechno-shtyrevoi zamedlyayushchei sistemy. Izvestiya VUZov. Prikladnaya nelineinaya dinamika. 2015. T. 23. № 1. S. 62−75.
22. Nakrap I.A., Savin A.N. Issledovanie prodolnogo raspredeleniya polei v periodicheskikh strukturakh s vyvodami energii. Materialy dokladov 25-oi Mezhdunar. Krymskoi konf. «SVCh-tekhnika i telekommunikatsionnye tekhnologii» (KryMiKo-2015). 2015. S. 147−148. ISBN: 978-1-4673-9414-7.
23. Savin A.N., Nakrap I.A., Vakhlaeva K.P. Metod razdeleniya vidov kolebanii pri raschete kharakteristik ZS TsSR v programme ANSYS HFSS. Ural Radio Engineering Journal. 2018. T. 2. № 4. S. 41−51.