0.2-THz Dual Mode Sheet Beam Traveling Wave Tube

Equipping the adjustable horizontal focusing electrodes (FEs), a dual mode electron gun providing different current beams, has been proposed and evaluated. Employing this tunable FE electron gun, a continuous wave (CW)/pulsed dual mode, 0.2-THz sheet beam traveling wave tube (SB-TWT) has been designed. The tube employs a high density and high current sheet beam for pulsed mode operation, and a reduced size and lower current sheet beam for the CW mode. This scheme provides CW mode increased efficiency and higher beam transmission factor than other, more conventional, dualmode techniques such as by changing the RF drive power. Using a 1.2-T uniform focusing magnetic field, both beams are predicted to have excellent transmission factor (more than 99%) to the collector through the 65-mm beam tunnel. Driven by the pulsed, high current electron beam, the 0.2-THz SB-TWT exhibits more than 100-W power over a 20-GHz bandwidth. Driven by the low current electron beam, the tube provides 20-dB gain and 10-W CW output power over the required bandwidth of 0.19 THz-0.21 THz.