[1] Gregory S N, Manfred K T, Michael I A P. The gyrotron at 50: Historical overview[J]. Journal of Infrared Millimeter & Terahertz Waves, 35, 325-381(2014).

[2] [2] Drumm O, Dammertz G, Thumm M. Design methods f mirrs in a quasioptical mode converter f a frequency steptunable gyrotron[C]Infrared Millimeter wave. 2002: 191192.

[3] Jin J, Thumm M, Piosczyk B. Novel numerical method for the analysis and synthesis of the fields in highly oversized waveguide mode converters[J]. IEEE Trans Microw Theory Tech, 57, 1661-1668(2009).

[4] Hirata Y, Mitsunaka Y, Hayashi K. The design of a tapered dimple-type mode converter/launcher for high-power gyrotrons[J]. IEEE Trans Plasma Science, 1, 142-146(2003).

[5] Rock B, Neilson J M, Vernon R J. A power-optimizing integrated design of a dual-frequency gyrotron quasi-optical mode converter[J]. IEEE Trans Plasma Science, 40, 1522-1529(2012).

[6] [6] Agapova M, Belov Y, Chirkov A, et al. Megawatt power dualfrequency gyrotrons f modern fusion facilities[C]2019 44th International Conference on Infrared, Millimeter, Terahertz waves. 2019: 627628.

[7] [7] Jin J, Gantenbein G, Jelonnek J, et al. Quasioptical mode converter f 1MW dualfrequency gyrotrons[C]2017 Eighteenth International Vacuum Electronics Conference. 2017.

[8] [8] Jin J, Gantenbein G, Ruess T, et al. Design of a quasioptical mode converter f a dualfrequency coaxialcavity gyrotron[C]2019 44th International Conference on Infrared, Millimeter, Terahertz waves(IRMMWTHz). 2019.

[9] [9] Prinz O, Gantenbein G, Thumm M. Advanced quasioptical mode converter f a multifrequency gyrotron[C]2008 IEEE International Vacuum Electronics Conference. 2008: 6466.

[10] [10] Ikeda R, Oda Y, Kobayashi T, et al. Development of multifrequency gyrotron f ITER DEMO at QST[C]2016 41st International Conference on Infrared, Millimeter, Terahertz waves(IRMMWTHz). 2016.

[11] [11] Liao Shaolin. Multifrequency beamshaping mirr system design f highpower gyrotrons: They, algithms methods[D]. Madison: University of Wisconsin at Madison, 2008: 155166.

[17] [17] Du Chaohai, Pan Shi, Liu Pukun. THz broadb quasioptical mode converter antenna system[C]2016 IEEE international conference on microwave millimeter wave technology(ICMMT). 2016.

[19] Prinz O, Gantenbein G, Liu Yinghui. Highly efficient quasi-optical mode converter for a multifrequency high-power gyrotron[J]. IEEE Trans Electron Devices, 56, 828-934(2009).

[20] Bogdashov A A, Denisov G G. Synthesis of the sequence of phase correctors forming the desired field[J]. Radio Physics & Quantum Electronics, 47, 966-973(2004).

[21] Vlasov S N. Transformation of a whispering gallery mode, propagating in a circular waveguide, into a beam of waves[J]. Radiofizika, 15, 14-17(1972).

[22] Vlasov S N, Orlova I M. Quasioptical transformer which transforms the waves in a waveguide having a circular cross section into a highly directional wave beam[J]. Radiophysics and Quantum Electronics, 17, 115-119(1974).

[23] Denisov G G, Kuftin A N, Malygin V I. 110 GHz gyrotron with a built-in high-efficiency converter[J]. International Journal of Electronics, 72, 1079-1091(1992).