Electron beam generation and transport for millimeter and THz tubes

Electron guns and magnetic circuits for high frequency RF sources present unique challenges. As the frequency increases, the size becomes reduced. This becomes a serious problem when feature sizes approach the tolerances that can be achieved with available fabrication and assembly processes. Periodic permanent magnet focusing becomes particularly difficult when the magnets must be enclosed within the tube vacuum. This presentation will describe the challenges and the designs being developed for millimeter and submillimeter wave RF sources.