Ring-Shaped Electron Gun for Floating Zone Refining Apparatus

Emission and focusing characteristics of an unique ring-shaped electron gun for a floating zone refining apparatus are presented and discussed. The ratio of the work current to the total beam current is theoretically given as a function of the accelerating voltage, filament current and gun dimensions, and compared with the experimental data. Based on these results, a floating zone refining apparatus whose maximum output is 6.5 kW, capable of refining various materials such as refractory metals, semi-conductors and ceramics, has been developed. The chemical analysis data of refined material are shown as an application example of the apparatus.