The project of third harmonic medium power W-band gyrotron A.S. Zuev, A.P. Fokin, M.Y. Glyavin, R.M. Rozental, A.S. Sedov and E.S. Semenov EPJ Web Conf., 195 (2018) 01024 Published online: 23 November 2018 DOI: 10.1051/epjconf/201819501024