Dielectrics for output windows of medium power gyrotrons Evgeny Serov, V.V. Parshin, S.V. Egorov, A.N. Konovalov, A.I. Makarov and K.V. Vlasova EPJ Web Conf., 195 (2018) 06014 Published online: 23 November 2018 DOI: 10.1051/epjconf/201819506014