A Compact Lightweight Electron Beam and Focusing System for Millimeter Wave TWTs

We propose to design compact electron gun and a focusing system to produce and transport a 25 kV and 0.4 A beam for use in a high-power W-band Traveling Wave Tube (TWT) amplifier. The magnet focusing system will transport this beam with a maximum average diameter of 0.3 mm through a beam tunnel with a maximum diameter of 0.5 mm over a minimum distance of 5 cm of the interaction circuit with 100 % beam transmission in the absence of RF. The electron gun will have a modulating anode to rapidly turn off the beam with a pulse repetition rate of up to 50 kHz with a minimum duty factor of 3 %. During the Option phase of this proposal, we will develop a complete mechanical design of the electron gun and a beam stick followed by thermal and structural analysis. The state-of-the-art alignment techniques like elastic averaging, kinematic coupling and quasi-kinematic couplings will be considered for achieving high precision and alignment of the various parts in the system.