Computer-aided TWT design

A new and inexpensive method of computing the large and small-signal gain, the efficiency, and the saturated power for helix type TWT's has been developed. The input data to the analysis are the physical dimensions of the helix, the surrounding vacuum structure, and the properties of the electron gun. The small-slgnal analysis is based on a field analysis of S. F. Paik, and the large-signal analysis is based on curve-fitting to the original works of Nordsieck, Rowe, Tien, and Cutler and Brangaccio. Experimental data on two helix tubes operated over extended bandwidths have shown the equations to correlate to within about 0.5 dB in output power.