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BELL SYSTEM TECHNICAL JOURNAL 



approximation, in the region where the grid potential is negative 

 with respect to the filament as shown in Fig. 10. Hence, in this 

 region (9) is satisfied for all practical purposes, and, therefore, the 

 proof of (8) follows directly. 



150 



140 



130 



tzo 



HO 



100 



90 



-5 -A -3 -2 -t Eg, VOLTS 



Fig. 10 — Relation between E and E for constant plate current 



