Possibilities of increase of gyrotron efficiency via frequency locking by external signalVladimir L. Bakunin, Gregory G. Denisov, Yury M. Guznov, Michael V. Morozkin, Yulia V. Novozhilova and Andrew S. ZuevITM Web Conf., 30 (2019) 09004DOI: https://doi.org/10.1051/itmconf/20193009004