Performance analysis of an insert cooling system for long-pulse operation of a coaxial-cavity gyrotron - Kalaria, P.C.; George, M.; Uly, S.; Avramidis, K. A.; Gantenbein, G.; Ruess, S.; Rzesnicki, T.; Thumm, M.; Jelonnek, J. (2018 IEEE International Vacuum Electronics Conference, IVEC 2018, 2018)