Development of a 500-watt CW traveling-wave tube at S/C band

The CW power level of reliable PPM helix-type traveling-wave tubes with over an octave bandwidth has been limited in the past to about 300 watts. A PPM focused TWT that has produced 500 watts of CW power over one octave in the S/C frequency band has been developed during the past year. This paper presents the design approach used, the construction details, and the measured performance. The tube is focused with a PPM array using Alnico 8 magnets. It employs a tungsten-tape helix structure to obtain operation over an octave. Some experimentation was done with radial focusing PPM structures. Results will be discussed. The design of the TWT is aimed specifically at a rugged construction for use in airborne equipment.