1.4: Design of a high-gain wideband high-power 220-GHz multiple-beam serpentine TWT

A new concept for a compact high-gain multiple-beam TWT amplifier is introduced. To illustrate the concept, we present the design of a three-beam 220-GHz serpentine TWT amplifier. MAGIC-3D particle-in-cell code simulation results predict that the device should be capable of a peak power of 73 W and saturated gain of 42 dB over an instantaneous bandwidth of 50 GHz (23%), when powered by three 100 mA, 20 kV, well-focused electron beams. This performance can be achieved in a very compact circuit length of only 1.5 cm - a significant advantage for THz electron beam devices where issues of fabrication tolerances, beam alignment, and electron interception are of critical importance.