Influence of mode competition and external wave frequency modulation on gyrotron frequency locking Yu.V. Novozhilova, V.L. Bakunin, A.V. Chirkov, Yu.M. Guznov, G.G. Denisov, A.P. Fokin, A.S. Shevchenko, N.I. Zaitsev and S.A. Zapevalov EPJ Web Conf., 149 (2017) 04021 Published online: 04 August 2017 DOI: 10.1051/epjconf/201714904021