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BELL SYSTEM TECHNICAL JOURNAL 



top portion of Fig. 3. The feedback voltage representing the right-hand 

 side of Equation 1 is plotted as a function of beam position. The electron 

 beam will have several. possible positions of equilibrium at points (_/>!, p2, 

 p3, pA, pS, p6 and p7) where the deflection line D erected from —e, repre- 

 senting the left-hand portion of Equation 1, crosses the feedback curve. 

 These are the only beam positions for which the deflection potential (signal 

 plus feedback) attains correct values for corresponding beam positions. 



BEAM POSITION 



Fig. 3 — Graphical representation of quantization. 



However, only positions pi, p3, pS and pi will be in a true state of equilib- 

 rium. This can be seen as follows: Consider the beam at point p?>\ if the 

 beam is perturbed toward the right, the feedback voltage tending to deflect 

 the beam to the left increases. The opposite action ensues if the beam is 

 perturbed in the left-hand direction. Point p?> is a true equilibrium point. 

 On the other hand, consider the beam at position />4. If the beam is per- 

 turbed to the right, the feedback voltage tending to deflect it to the right 

 increases and the beam continues to move until it reaches the equilibrium 



