1332 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1957 



The switching coefficient, s„ , for circular flux reversal, is derived as 



-3 



OlB 



(87rB.r2')10 

 P2(l — a^) cos 6 



4a (1 



,a 



(1 - a - bY^ - (1 - hY 

 Pi 



+ 



h) 



a 

 2 



+ (1 - bV 



4(1 - 6) l\ 

 3 ■^21' 



(20) 



or 



= Co 



(g.r2-)10"' 

 P2 cos 6 



(oe-fisec). 



(21) 



Table II gives Ccirc as a function of a and pi/p2 . 



The switching coefficient s^ for axial flux reversal is derived as 



"7B 



V5,r2'lO~' 



1 - 4a' + a'(3 - 4 In aY 



P2 cos 6 



1 - a^ 



ii I — 



\P2 



(22) 

 (23) 



cos d I 



Table III gives Caxiai as a function of "a". 



Since, as explained for the solid wire case, the eddy current density- 

 vectors for circular and axial flux reversal are in quadrature, 



s„ (axial) + s„, (circular) 



s^, (helical) = 



2 



(24) 



Substitution of (21) and (23) into (24) gives the required expression; 



^.(helical) = i C-^r.^C.^,.\{B,ri)\Q-\ ^^5) 



A number of composite wire samples have been prepared and evalu- 

 ated. These include nickel on nichrome and nickel on copper. The switch- 



