Evgeniy Sheshin

The results of a study of the emission characteristics of a molecular-sprayed oxide thermocathode based on triple carbonate of alkaline earth metals with an emission layer thickness of ~1 µm in the operating temperature range of 590-730 °C. are presented. The results are in good agreement with those obtained earlier for a serial oxide thermocathode with an emission layer thickness of ~100 µm applied by pulverization, and correspond to the model of a "spotted cathode" - a superposition of emission spots at different stages of activation. An idea of the activation phenomenon occurring at a given temperature in a certain range of values of the electric field strength on the surface of emission spots is detailed both with an increase and a decrease in the anode voltage. The energy spectra of the emitted electrons of a separate emission spot with a half-height width of ~100 meV have been obtained. The values of the potential change of the emitting surface of the cathode within the probed region of 0.9 V and the potential drop on the emission layer under the probed region of 4.1 V were measured.

Московский физико-технический институт (национальный исследовательский университет) 141700, Долгопрудный, Институтский пер., 5 Статья поступила в редакцию 13 марта 2023 г.

In this paper, we experimentally compare the field emission characteristics of two different cathodes based on polyacrylonitrile fibers (PAN fibers) and carbon nanotube fibers (CNT filaments). The main purpose of the study was to compare the field emission properties of materials for the cathode unit of a cathode luminescent lamp. The current-voltage, current and watt-watt characteristics of the fabricated cathodes were measured. A comparison of the current-voltage characteristics of cathodes made of the two studied materials shows that the minimum field for the occurrence of field emission current for a cathode made of a CNT filament (accelerating voltage in the diode version of measurements is about 625 V) is approximately 3 times lower than for a cathode made of PAN fibers (accelerating voltage is about 1850 V. Accordingly, the current value of about 100 μA for a cathode based on a CNT filament is achieved at an accelerating voltage of about 1300 V, and for a cathode based on PAN fibers, about 2630 V. Structural changes in cathodes were studied using scanning electron microscopy methods. Based on the totality of the results, it was concluded that it is preferable to use a CNT filament as a cathode material. The emission current of a cathode based on a CNT filament, when a constant high voltage is applied, demonstrates an increase during the transition period and reaches a stable value of more than 75 μA, apparently due to the activation of additional emission centers when a high accelerating voltage is applied. The paper also analyzes the factors that determine the efficiency of light sources created on the basis of the materials studied in the work.