A study of scandia and rhenium doped tungsten matrix dispenser cathode

Scandia and rhenium doped tungsten powders were prepared by solid–liquid doping combined with two-step reduction method. The experimental results show that scandia was distributed evenly on the surface of tungsten particles. The addition of scandia and rhenium could decrease the particle size of doped tungsten, for example, the tungsten powders doped with Sc2O3 and Re had the average size of about 50 nm in diameter. By using this kind of powder, scandia and rhenium doped tungsten matrix with the sub-micrometer sized tungsten grains was obtained. This kind of matrix exhibited good anti-bombardment insensitivity at high temperature. The emission property result showed that high space charge limited current densities of more than 60 A/cm2 at 900 °C could be obtained for this cathode. A Ba–Sc–O multilayer about 100 nm in thickness formed at the surface of cathode after activation led to the high emission property.

On the surface of Sc2O3 and Re doped tungsten matrix, Sc2O3 is stable during heating up to 1500 K or under ion bombardment, indicating that Sc and Re co-doped matrix shows good anti-bombardment insentivity. Figure optionsDownload as PowerPoint slide