A Novel Tunable PCM Focusing System for a 220 GHz Sheet Beam Electron Gun

Sheet beam electron gun and focusing system are key parts of sheet beam traveling wave tube. In this paper, a 220 GHz sheet beam electron gun is designed and a novel tunable periodic cusped magnet (NTPCM) focusing system for this sheet beam electron gun is proposed. The beam current of the designed sheet beam electron gun is 0.13 A at 22 kV beam voltage, and the sheet beam size at beam waist is around 0.5 mm × 0.1 mm. Furthermore, the simulation results show that the sheet beam with current density greater than 260 A/cm
²
can transport more than 90 mm under the focusing of this NTPCM.