Study of 1-THz 4th-harmonic gyrotron

Du, Chao-Hai and Li, Fan-Hong and Pan, Shi and Liu, Pu-Kun and Zhang, Liang and He, Wen-Long and Yin, Hua-Bi and Ronald, K. and Cross, Adrian W. (2019) Study of 1-THz 4th-harmonic gyrotron. In: 12th UK-Europe-China Workshop on Millimetre Waves and THz Technologies (UCMMT 2019), 2019-08-20 - 2019-08-22, Queen Mary University of London.

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    Abstract

    A preliminary design of a 1-THz gyrotron based on the fourth harmonic operation is presented. The cylindrical-waveguide TE4,8 mode is selected as the operating mode. Considering the weak beam-wave coupling strength in a 4th-harmonic open-cavity interaction circuit at the frequency of 1 THz, this paper proposes applying low-temperature cooling, for example applying liquid nitrogen, to increase the limit of the Q factor and extend the effective length of the cavity resulting in a significant enhancement of the interaction efficiency and suppression of ohmic losses. Applying multi-mode time-domain theory in the simulation, it was found that although the competing third-harmonic TE3,6 mode was excited first, the fourth-harmonic TE4,8 mode finally dominates in the steady state regime.