A LARGE SIGNAL THEORY OF TRAVELING-WAVE AMPLIFIERS 371 

 11. A QUALITATIVE PICTURE AND CONCULSIONS 



We have exhibited in the previous sections the most important non- 

 linear characteristics of the traveling wave ampUfier. Xumerical compu- 

 tations based on a model of 24 electrons have been carried out for more 

 than twenty cases covering useful ranges of design and operating parame- 

 ters. The results obtained for the saturation Eff./C may be summarized 

 as follows: 



(1) It decreases with C particularly at large values of QC. 



(2) For C = 0.1, it varies roughly from 3.7 for QC = 0.1 to 2.3 for 

 i}C = 0.4, and only varies slightl}^ with h. 



(3) For C = 0.15, it varies from 2.7 to 2.5 for QC from 0.1 to 0.2 and 

 \i corresponding to the maximum small-signal gain. It varies slightly 

 with h for QC = 0.2. 



(4) It is almost constant between k — 1.25 and 2.50. 



In order to understand the traveling-wave tube better, it is important 

 to have a simplified qualitative picture of its operation. It is obvious that 

 to obtain higher amplification, more electrons must travel in the region 

 where the circuit field is positive, that is, in the region where electrons 



-1 



SP-by 



Fig. 8(d) — V versus <p — by for QC = 0.2, k = 2.5, b for m = mi (max) and 

 '' = 0.1 (Case 10). 



