Millimeter dual helix traveling-wave tube

The program objective is to develop a TWT in which dual coupled helix slow-wave circuits interact with dual beams. The TWT is to be capable of amplifying high pulsed RF power over wide bandwidths with sufficient gain and efficiency suitable for electronic warfare applications. The circuit design with dual helices coupled by connecting straps, which was developed on previous contracts, shall be utilized for obtaining the performance requirements. During the first contract, effort was directed toward study of the circuit structure and a theoretical study of both single beam and dual beam electron guns. Circuit structures consisting of countrawound helices were investigated. Impedance, phase velocity and dielectric loading factor have been measured for various circuit structures, including adjacent helices as well as individual helices separated by different sized connecting straps. Based on the theoretical gun investigations, two scaled experimental electron guns were designed and evaluated using an electrostatic demountable beam analyzer. Two C-band tubes were packaged, tested and evaluated at various modes of operation.