Publication Date:
2016-03-03
Description:
A technique to launch a circular TE 13 mode to interact with the helical electron beam of a gyrotron travelling wave amplifier is proposed and verified by simulation and cold test in this paper. The high order (HOM) TE 13 mode is excited by a broadband Y-type power divider with the aid of a cylindrical waveguide system. Using grooves and convex strips loaded at the lateral planes of the output cylindrical waveguide, the electric fields of the potential competing TE 32 and TE 71 modes are suppressed to allow the transmission of the dominant TE 13 mode. The converter performance for different structural dimensions of grooves and convex strips is studied in detail and excellent results have been achieved. Simulation predicts that the average transmission is ∼−1.8 dB with a 3 dB bandwidth of 7.2 GHz (91.5–98.7 GHz) and port reflection is less than −15 dB. The conversion efficiency to the TE 32 and TE 71 modes are, respectively, under −15 dB and −24 dB in the operating frequency band. Such an HOM converter operating at W-band has been fabricated and cold tested with the radiation boundary. Measurement from the vector network analyzer cold test and microwave simulations show a good reflection performance for the converter.
Print ISSN:
1070-664X
Electronic ISSN:
1089-7674
Topics:
Physics
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