TRAVELING-WAVE TUBES 19 



discloses that the allowable range of velocity Av is of the order of 



A^ ;:^ ± Cuo (2.44) 



Thus, the allowable difference between the phase velocity of the circuit and 

 the velocity of the electrons increases as circuit impedance and beam current 

 are increased and decreases as voltage is increased. 



We have illustrated the general method of attack to be used and have 

 introduced some of the important parameters concerned with the circuit 

 and with the overall behavior of the tube. In later chapters, the properties 

 of various circuits suitable for traveling-wave tubes will be discussed in 

 terms of impedance and phase velocity and various cases of interest will be 

 worked out by the methods presented. 



