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ISSN Печать: 0040-2508
ISSN Онлайн: 1943-6009
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Selecting the Starter Cathode for the Pulsed Magnetron with a Cold Secondary-Emission Cathode
Краткое описание
The paper presents results of durability investigations made for a variety of dispenser cathodes with the aim of selecting the type of the starter cathode for the three millimeter band magnetron with a platinum secondary-emission main cathode. The disk starter cathode, placed instead of one of the end shields, is intended for triggering the secondary emission at the beginning of the anode voltage pulse. Along with standard impregnated cathodes, cathodes with silicon or scandium oxide additions to the standard impregnation and those with an osmium film applied over the emissive surface have been studied. The tests were done after an express method, using a specially designed test bed. The results have shown that all four types of cathodes were capable of providing the required durability of 5000 hours, given the available reserve of their active substance and an operating temperature ensuring a 1 A/cm2 density of the emission current. However, the best results with respect to durability and reproducibility of performance were shown by the cathodes with an osmium film. They have been chosen as starter cathodes to be used in durable magnetrons. The current tests of such magnetrons have proven the validity of this choice, as the operating time of all three devices has reached 5000 hours, which greatly exceeds the results previously-obtained for this waveband.