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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.
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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