An Exact Hot-Tube Solution For Thin Tape Helix Traveling-Wave Tube*

The exact hot-tube dispersion relation for a thin tape helix traveling-wave tube (TWT) is derived for the first time, based on its exact cold-tube solution [1]. This is an attempt to provide a reliable determination of the Pierce parameters, in particular the "AC space-charge" parameter \textit{QC}, for a realistic TWT. The determination of \textit{QC} remains an outstanding issue [2]. The numerical results from the exact formulation will be compared with other approximate models of TWT that were commonly used in the literature for \textit{QC }[3]. [1] D. Chernin, et al., \textit{IEEE Trans. ED} \textbf{46}, 7 (1999). [2] D. H. Simon, et al., \textit{Phys. Plasmas} \textbf{24}, 033114 (2017). [3] G. M. Branch and T. G. Mihran, \textit{IRE Trans. ED} \textbf{2}, 3 (1955).