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Tungstate cathodes have been prepared by impregnating a mixture of the barium-strontium tungstate and zirconium hydride at 1840 °Cb. Emission characteristics and evaporation properties were tested. The result shows that the dc emission current density reaches 4.30A/cm2 at 1000 °Cb, 7.54A/cm2 at 1050 °Cb, 9.43A/cm2 at 1100 °Cb. The evaporation rate of the cathode is lower than an uncoated aluminate...
In order to enhance the emission current, reduce the operating temperature and prolong the lifetime of the pure W filament cathode for application in high-power (i.e., more than 10KW) continuous wave magnetron tube, a novel Y2O3-Gd2O3-HfO2 impregnated W base direct-heated cathode (Y-Gd-Hf-O impregnated cathode) has been developed. At 1700°br, the dc emission density of the Y-Gd-Hf-O impregnated cathode...
In this paper we mainly describes the research progress in a kind of ammonium perrhenate impregnated W matrix Ba-W cathode, which includes the preparation of W-Re matrix by impregnated ammonium perrhenate solution and the cathode properties testing. The lifetime testing results show that the emission current, after 16056h lifetime at a temperature of 1000 °Cbr, has still increased more than 8% with...
In order to enhance output power and prolong lifetime of the high-power continuous wave magnetron tubes, a novel La2Zr2O7 impregnated cathode is adopted to enhance the thermionic emission. In this abstract, we compare the thermionic emission ability of this cathode with traditional pure W filament cathode. Experimental results show that this cathode can provide the same thermionic emission with at...
Energy and local distribution of electron around the cathode have been simulated in a 30kW continuous wave magnetron tube which operates in normal output power. According to the simulation results, it is clearly that the cathode of magnetron is bombed by low energy electrons mostly among 0 and 2keV. Based on the fact that most of the back bombardment electron belong to low energy electron, when the...
The oxide cathode is one of the most commonly used electron sources in vacuum tubes. Continual improvement of vacuum tubes requires better and better current emission performance of their electron sources. In this context, new type oxide cathodes have been emerging incessantly in the past century, such as Ni sponge oxide cathode, rare oxide cathode and reservoir oxide cathode. Nonetheless, there is...
Different treatments on the cathode surface are adopted to enhance the secondary electron emission(SEE)of the cathode in high-power continuous wave magnetron tubes, which show that SEE coefficient of the pure tungsten cathode sprayed sand for coarseness and coated W-Re5%wt film is higher than that of untreated pure tungsten cathode.
In this paper we mainly describes the research progress in a kind of ammonium perrhenate impregnated Ni sponge oxide cathode, which includes the preparation of Ni-Re sponge layer by impregnated ammonium perrhenate solution and the cathode properties testing. The testing results show that the pc emission current density of the cathode reaches 35.6A/cm2 with a 10μs pulse width at a temperature of 850U...
In this paper we mainly describes the research progress in a kind of plasma spraying coating oxide cathode, which includes the preparation of Ni-Sc sponge layer and plasma spraying Sc doped coating and the properties testing. The testing results show that the dc emission current density of the cathode is over 4A/cm2 and the pulse emission current density reaches 103 A/cm2 with a 1µs pulse width at...
The oxide cathode presented here is a reservoir dispenser oxide cathode based on the improved designs of the structure with a reservoir cell, the Ni sponge with the controlled porosity, and the emission materials in the cell. Its excess Ba comes from the reservoir emission material in the cell of the cathode. The excess Ba can easily diffuse to the surface of the cathode to emit electrons through...
In this paper, a gas-liquid synthetic method has been used to prepare the carbonates for decreasing the size of the carbonate grain, optimizing the shape of the grain, lowering the complexity of preparing technology and improving the emission characteristics of the cathode. Fig.2 is the SEM of the carbonates which is synthesized under the condition of 0.125 mol/1 concentration, 2.51/min gas rate and...
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