CW subterahertz gyrotron operating at high cyclotron harmonics Ilya Bandurkin, Nikolay Zavolsky, Yuri Kalynov, Vladimir Manuilov, Ivan Osharin, Andrey Savilov and Alexander Fiks ITM Web Conf., 30 (2019) 09001 Published online: 27 November 2019 DOI: 10.1051/itmconf/20193009001