Shikai Qi

Secondary electron emission of the cathode in high-power continuous wave magnetron tubes

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.

Preparation and performance of the ammonium perrhenate impregnated W matrix Ba-W 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 3.0 A/cm2 DC current.

Emission uniformity of the ammonium perrhenate impregnated Ni sponge oxide cathode

In order to improve emission performance of the Ni sponge oxide cathodes, an ammonium perrhenate impregnated Ni Sponge Oxide Cathode has been developed by IECAS. In this paper we mainly describe the research on the emission uniformity of this cathode with the thermal electron spectrometry analysis and the work function distribution test. The test results indicates that the emission uniformity of the Ni-Re sponge oxide cathode fabricated by this liquid-solid mixing method is better than that of the conventional Ni-Re sponge oxide cathode fabricated by the solid-solid mixing method.

Influence of new material and technology on oxide cathode performance

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 still room for further improvement. In this paper we mainly describe the research process on Ni-Sc sponge oxide cathode, ammonium perrhenate impregnated Ni sponge oxide cathode and plasma spraying oxide cathode. Moreover, we also developed the quick warm-up cathode depend on oxide cathode low operation temperature and simple structure.

Study of emission properties and evaporation rate of impregnated tungstate cathode

Tungstate cathodes have been prepared by impregnating a mixture of the barium-strontium tungstate and zirconium hydride at 1840 °C_b. Emission characteristics and evaporation properties were tested. The result shows that the dc emission current density reaches 4.30A/cm² at 1000 °C_b, 7.54A/cm² at 1050 °C_b, 9.43A/cm² at 1100 °C_b. The evaporation rate of the cathode is lower than an uncoated aluminate cathode.

Evaporation and lifetime of the ammonium perrhenate impregnated W matrix Ba-W 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 evaporation rate measuring and the lifetime testing of the cathode. The evaporation rate measuring results shows that the evaporation rate of the cathode is 8.66×10-10g.cm-2s-1 at 1000°Cbr measured by a quartz crystal oscillating method. The lifetime testing results show that the emission current, after 22392h lifetime at a temperature of 1000°Cbr, has still increased more than 6% of the initial 3.0 A/cm2 DC current density.

Study on a novel Y 2 O 3 -Gd 2 O 3 -HfO 2 impregnated W base direct-heated cathode

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 can reach to 10.5A/cm². After 3600 h operation of the cathode under 1600°br, the dc emission current density of it is still stable at the initial value of 1.5A/cm².

Thermionic emission of a novel cathode applied in high-power continuous wave magnetron tubes

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 least 300 ° lower than pure W filament cathode.

Emission simulation and secondary electron emission measurement of the cathode in high-power continuous wave magnetron tubes

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 energy of incident electron is among 0 and 2keV, the secondary electron emission yield (SEEY) of cathodes provided with different mass percent Re doping W-Re alloy are measured, eventually, we obtain the maximum SEEY of W-Re alloy cathode when adopted by 5%Re doping.