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In order for practical applications in Vacuum Electron Devices (VEDs), the robustness of Scandia Doped Dispenser (SDD) cathodes has been widely concerned. Machinability, emission performance from machined surface, recovery of emission after poisoning; air exposure and ion bombardment have, thereby, been studied. The investigation demonstrated that the cathodes can be successfully machined by normal...
Since the cathodes with machined surfaces are required for the practical applications in some high-power vacuum electron devices, the characteristics of nanosized-scandia-doped dispenser (SDD) cathodes with machined surfaces have been investigated, especially in dc applications. In order to reopen the surface pores, which may be smeared by machining procedure, the cathode surface was washed by Ethylene...
The scandia doped tungsten powders have been obtained by a new method of spray drying combined with two-step reduction in hydrogen atmosphere. The impregnated cathode prepared with the obtained powders has an excellent emission capability of 121 A/cm2 at 950° b in pulsed condition. The DC life test result indicates that the emission current density of 40 A/cm2 has lasted up to 4000 hours.
Since the cathodes with concave surfaces are required for the practical applications in most high-power vacuum electron devices, characteristics of nanosized-Scandia Doped Dispenser (SDD) cathodes with concave surfaces have been investigated, especially in dc applications. A space charge-limited (SCL) dc current density of over 50 A/cm2 has been measured at 1000 °Cb. An on-going life test with a dc...
In this paper, a new fabrication method of barium-calcium aluminate impregnated cathodes is reported. Barium-calcium aluminates were fabricated by one-pot hydrothermal reaction. The sintering temperature of the material is lower than the conventional method about 100 °C and the impregnation temperature is decreased about 50 °C. The pulsed emission current density of this cathode could reach 12.64A/cm...
In order to improve the mechanical strength and machining properties of Scandia Doped Dispenser (SDD) cathodes when they are applied into Vacuum Electron Devices (VEDs), an effort has been expended to increase the W grain sizes while maintaining the uniform doping of nanosized Scandia particle. By an improved liquid-solid (L-S) doping process, powders composed of W grains of about 1–2 micron in diameters...
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