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BELL SYSTEM TECHNICAL JOURNAL 



curves. For the latter it is quite easy to obtain log is but not so easy 

 to determine log iao- 



In Fig. 17 we have thus shown log His vs. V P for constant b and T 

 but varying /x. Had log ijiao been plotted the curves would have been 



0.4 



0.2 



-0.4 



■0.6 



-0.8 



-1.0 



-2.0 



-2.2 



-2.4 



20 40 60 80 100 120 140 160 ISO 200 



VT" (VVOLTS PER cm) 



Fig. 17 — Variation of average emission current with applied field for hill and valley 

 checkerboard; p. variable, 7' and b fixed. 



