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THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1956 



LL 



0.9 



0.8 



0.7 



0.6 



0.5 



0.4 



0.3 



0.2 



0.1 



0.38 



0.36 



0.34 



0.32 



0.30 



0.28 



0.26 



0.24 



0.22 



0.20 



0.18 1? 



0.1 6 



0.14 



0.12 



0.10 



0.08 



0.06 



0.04 



0.02 



6 7 8 9 



10 



11 12 13 



14 



Fig. 9 — Showing quantities related to the effect of the space charge force in 

 the drift region on the outermost non-thermal electron. (See equation 28.) 



i 



We can now substitute for transit time in terms of distance and Lang- 

 muir's well known potential function/^ —a. The value of this parameter, 

 for the case of spherical cathode-anode geometry in which we are in- 

 terested, depends only on the ratio fe/f which is equal to Vc/rg . (Because 

 of their frerjuent use in gun design, certain functions of —a are included 

 here as Table I.) In terms of —a, then, the potential in the gun region 



