570 



BELL SYSTEM TECHNICAL JOURNAL 



switch voltage is equal to or greater than the breakdown voltage of one gap. 

 The gaps will operate for all switch voltages up to a value equal to twice the 

 breakdown voltage of one gap when both gaps will break down without the 

 addition of trigger. This, then, is the maximum operating voltage and the 

 ratio of maximum to minimum operating voltage is two to one on the basis 

 of this simple picture. 



FROM 



CHARGING ' 



CHOKE 



FROM 

 TRIGGER. 

 CIRCUIT 



J 



PULSE 

 FORMING 

 NETWORK 



/V ' j\r- 



05 MM 



"T 



V= 1600 



E= 3 2 000 V/CM 



-_r 



Fig. 4 — -Line modulator circuit with fixed gap switch composed of five 0.5 mm. air gajjs 

 triggered electrical!}'. 



In the case of the three-gap circuit, Fig. 5 (b), gaps 1 and 2 may be broken 

 down by the simultaneous application of a trigger pulse through capacity 

 coupling. The circuit elements can be so chosen that gap 1 first breaks down 

 leaving enough trigger on gap 2, over and above that furnished by the switch 

 voltage, to break it down. The full switch voltage is then applied across 

 gap 3 and it will break down for values of switch voltage in excess of the 



