8-fold helically corrugated interaction region for high power gyroresonant THz sources

Donaldson, Craig R. and Zhang, Liang and Harris, Michael and Beardsley, Matthew J. and Huggard, Peter G. and Whyte, Colin G. and Cross, Adrian W. and He, Wenlong (2021) 8-fold helically corrugated interaction region for high power gyroresonant THz sources. IEEE Electron Device Letters, 42 (10). pp. 1544-1547. ISSN 0741-3106 (https://doi.org/10.1109/LED.2021.3105435)

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Abstract

A manufacturing study of a 0.372 THz 8-fold (8F) helically corrugated interaction region (HCIR) and measurement of its wave dispersion characteristics are reported. This demonstrates the structure’s suitability as the electron beam / electromagnetic wave interaction region in a high power frequency tunable Gyroresonant THz source. The 8F HCIR has an eigenmode, which is ideal for broadband tuning, created by the coupling of the TE61 and TE23 modes. Maximum power handling of 14 times larger than a 3-fold HCIR at the same frequency is calculated. A TE11 to TE61 7-fold (7F) helically corrugated waveguide (HCW) mode converter, needed to measure the wave dispersion of the 8F HCIR, was designed and constructed. Negative aluminium mandrels of the 7F HCW mode converter and 8F HCIR were manufactured. Copper structures were constructed through electroforming. The measured wave dispersion of the 0.372 THz 8F HCIR agreed well with simulated dispersion characteristics.