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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...
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...
To find the changes of surface compositions during life time of the Scandia-doped impregnated dispenser cathodes, two cathodes have been tested at an activation temperature of 1150°CB-Mo and an operation temperature of 1000°CB-Mo, respectively, in an AES system up to more than 7,000 hours. Surface compositions were monitored in-situ at intervals. The tested results have been reported and discussed...
The surface analysis of scandate cathodes has revealed that active substances of Ba, Sc and O formed a layer on the surface of the cathodes. By using First-principles calculation method, the W and Ba-Sc-O-W systems were calculated to study the effect of active elements on the work function of the cathode.
Special emission behaviors have been observed historically and recently on scandate cathodes. For a better understanding of the phenomena, we investigated the correlation between emission properties of scandia-doped dispenser cathodes and their surface features. The influence of external electric fields on the semiconductor layer of the cathodes is suggested to be mainly responsible for the special...
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