Design of a second cyclotron harmonic gyrotron oscillator with photonic band-gap cavity

• Published in: Journal of physics. D, Applied physics Applied physics, 2011-07, Vol.44 (29), p.295102
• Main Authors: Gaofeng, Liu, Xiaoan, Chen, Changjian, Tang
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Fundamental areas of phenomenology (including applications); Optical elements, devices, and systems; Optical materials; Optical waveguides and coupleurs; Optics; Photonic bandgap materials; Physics
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/44/29/295102

A photonic band-gap cavity (PBGC) gyrotron with a frequency of about 98 GHz is designed. Theoretical analyses and numerical calculations are made for the PBGC operating at fundamental and second cyclotron harmonic with a TE 34 waveguide mode to demonstrate the beam–wave interaction. The results show that mode competition is successfully eliminated in the PBGC using mode selectivity and choosing the appropriate operating parameters. As a result, the second harmonic PBGC gyrotron operating at TE 34 mode achieves a higher output efficiency than that of the fundamental. It is also demonstrated that, in the case of the chosen parameters for TE 34 waveguide mode, the use of PBG structure in the second harmonic gyrotron brings about not only a lower operating B -field but also a weaker mode competition. The results show that the high-order electromagnetic mode can be developed to interact with the high cyclotron harmonic using the selectivity of the PBGC, which gives an encouraging outlook for the development of high-harmonic gyrotrons.