Magnetic Focusing System for 300 GHz Sheet Electron Beam Traveling-Wave Tube Using Periodic Permanent Magnet

Abstract

We present the design study of magnetic focusing system for sheet electron beam which is used in a 300 GHz traveling-wave tube. The motivation of this work is that the sheet electron beam, with a periodic permanent magnet (PPM), can generate moderate RF output power at submillimeter and terahertz regime while having compact system size. It was shown in previous researches that PPM is capable of stable two-plane focusing of sheet electron beam. There are many variants of PPM, such as periodically cusped magnet (PCM), wiggler, and PCM with quadrupoles. In this work, we concentrate on two-plane PCM and wiggler.