Nanocarbon-Modified Metal Porous Cathodes with High Durability for Application in Microwave Devices
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rbon-Modified Metal Porous Cathodes with High Durability for Application in Microwave Devices T. M. Krachkovskayaa*, L. A. Melnikovb, O. E. Glukhovac,d, V. V. Shunaevc, and P. D. Shalaeva a
“Almaz” Research and Production Enterprise, Saratov, 410033 Russia Gagarin State Technical University of Saratov, Saratov, 410054 Russia c Saratov State University, Saratov, 410012 Russia d I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, 119146 Russia *e-mail: [email protected] b Yuri
Received March 27, 2020; revised April 9, 2020; accepted April 10, 2020
Abstract—The paper presents the calculations of the physical and energy parameters of nanocarbon structures with the components of a metal-porous cathode active substance. Obtained results match experimental data. It has been experimentally determined that the active substance modified by the sulfoadduct of carbon nanoclusters has an evaporation rate 1.5 times lower than the typical one. Tests of nanocarbon-modified cathodes as part of a travelling wave tube for space applications have shown them to have a durability of 1740 800 h at a 0.645-A/cm2 current density on collector. Keywords: carbon nanoclusters, metal-porous cathode, Astralene®, Ugleron®, durability, microwave devices. DOI: 10.1134/S106378502007010X
At the present time requirements to electric vacuum devices have significantly increased. Their reliability, durability as well as the stability of the electrical characteristics, are largely determined by the emission reliability and durability of the cathodes, i.e., the emissivity of the cathode and its stability during operation. The emissivity and durability of the cathode are due to both internal and external factors. The internal factors that determine the potentially stable emission properties of the cathode and its typical durability are the composition and evaporation rate of the active substance, the composition and porosity of the sponge, the purity of the cathode node materials, and the operating mode. The favorable external conditions are, first, high vacuum and the absence of cathode-poisoning gases directly in the vacuum volume of the device shell; second, the absence of contamination on the electrode surfaces, which can be released into the vacuum volume under the action of thermal and electric (current) loads and poison the cathode; third, the absence of easily pulverizing materials in the intratube armature, which can lead to irreversible poisoning when depositing on the cathode; and, fourth, the absence of breakdowns between the electrodes (especially between the cathode and other electrodes), causing the destruction of the cathode. Establishing the first two of these conditions largely depends on the methods and modes of the pro-
cessing of the device during pumping and training, on the methods of preliminary mechanical, thermal, and the chemical treatment and cleaning of intratube electrodes, parts, and assemblies, as well as the physical and chemical properties of the structural materials of the intratube armatur
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