Synthesis of folded waveguide TWT

The folded waveguide traveling-wave tube (FWTWT) has the advantage of higher power capability, with reasonable bandwidth, compared with helix TWT and coupled-cavity TWT. The method of synthesizing the main parameters of FWTWT is studied and used for designing Ka-band devices. To verify the synthesis, the results are compared with those generated by simulation codes such as HFSS and three-dimensional particle-in-cell (PIC) code for the estimation of cold and hot characteristics. From the synthesis, based on Pierce´s small signal theory, it is shown that plasma frequency sensitivity affects the growth rate. A Ka-band folded waveguide TWT has been designed from the synthesis and is under fabrication. Theoretical and experimental details are presented.