Emission Property of Sc2O3-W Matrix Cathode and Generation of High Current Density Sheet Beams for THz Vacuum Electron Sources

Sc2O3 doped tungsten matrix dispenser cathode prepared by liquid-liquid doping method exhibits high emission property, i.e., space charge limited current density reaches 48 A/cm at 850 Cb together with the slope of 1.44 has been obtained. Scanning electron microscope observation shows that the matrix has sub-micrometer microstructure, which is favorable for the diffusion of active substance from the inner part of cathode to the cathode surface. A multi-layer of active substance of Ba, Sc, O formed on the surface of the cathode leads to its conspicuous emission performance. Based on this kind of cathode, rectangular electron beam of 100 μm × 600 μm and square beam of 600 μm × 600 μm have been obtained. A uniformly distributed space charge limited current density of more than 50 A/cm can be drawn out from the emitting area at 950 Cb and keeps stable for at least several hundred hours.