Long lifetime tests of 3-mm wave magnetrons with secondary-emission cathode

The basic purpose of this work consists in clarifying the potential durability of magnetrons with platinum cathodes. An experimental 3-mm range device, designed for high resolution radar, was chosen for the tests. This device utilises the first backward harmonic of the N/4-2 mode as the working one. It had a platinum secondary-emission cathode in the interaction space and a disk auxiliary cathode located in place of one of the end screens. The obtained results indicate that the creation of magnetrons for the 3 mm wavelength with a lifetime of 5000 hours and more is quite a real task. It is became obvious that to solve it is impossible without careful elaboration of the magnetron construction with the purpose of guaranteeing cathode centering for such a long time. Besides, it is necessary to carry out an additional investigation of auxiliary cathode mode conditions in such a magnetron for minimizing the precipitation of evaporation products from the thermionic cathode onto the secondary-emission cathode.