Terahertz gyrotrons with quasi-regular cavities I.V. Osharin, I.V. Bandurkin, Yu.K. Kalynov, S.V. Kuzikov and A.V. Savilov EPJ Web Conf., 149 (2017) 05018 Published online: 04 August 2017 DOI: 10.1051/epjconf/201714905018