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The relationship between emitted energy spectrum and multipactor threshold of impedance transformer is investigated numerically in this paper. Secondary electron yield remains the same, while the emitted energy spectrum changes. Numerical simulations are provided for different cases of emitted energy spectrum. We analyze the practicability of this method in theory and simulation. Simulation results...
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...
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...
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.
To improve emission performance of the Ni sponge oxide cathodes, a Ni–Re sponge was prepared by impregnating an Ni sponge in an ammonium perrhenate solution and then a cathode was fabricated using this Ni–Re sponge. At 850 , the dc emission current density of a typical impregnated Ni–Re sponge cathode is 5.21 and the pulsed emission...
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...
Si quantum dots formed in a Si/SiGe two-dimensional gas (2DEG) are a promising candidate for the realization of solidstate quantum computation. To achieve effective Schottky gating for charge manipulation in the normal structures, a sharp phosphorus turn-off is required. We investigated phosphorus surface segregation in relaxed Si0.7Ge0.3 epitaxially grown by rapid thermal chemical vapor deposition...
In this paper, the synergetic action of UV-Fenton catalytic oxidation and nano-TiO2 photocatalytic to treat Azocarmine G dye wastewater was researched. The results show that the best conditions for the treatment of 250mL Azocarmine G dye wastewater are: the dosage of 30% H2O2 is 1mL; the dosage of 0.1mol/L FeSO4·7H2O is 3mL; the dosage of nano- TiO2 is 1g; pH is 4; illumination distance is 21cm. In...
A novel fiber-optic localized plasma resonance (FO-LPR) biosensor composed of a U-shaped optical fiber was proposed and demonstrated in the present study. The U-shaped optical fiber was fabricated by a femtosecond laser micromachining system. It was 105 mum in depth measured from the surface of the polymer jacket layer and 80 mum in width in the jacket layer. After treatment of annealing, the mean...
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