1.330 THE BELL SYSTEM TECHNICAL JOURXAL, NOVEMBER 1957 



When a equals 0, t equals 0, so the constant of integration is zero. When 

 a equals 1, t equals Ts , so 



s^ = TXH - //.) = 



10 (oe-Atsec; 



(18) 



15 p cos d , 



Comparison to the corresponding bulk flux reversal case indicates that 

 the wall motion mechanism is more lossy by a factor of 2.4. 



3.2 The Composite Magnetic Wire 



It is apparent from the switching data of Fig. 9 that for reasonably 

 sized solid wires (ro > 1 mil) the switching coefficient Sw is unreasonably 

 high. The typical ferrite memory toroid, for example, when used as a 

 memory element has an s», of 0.6 oersted-microseconds. The only possi- 

 bility for high speed coincident-current operation for solid magnetic wires 

 is that the material have a high coercive force He , a conclusion not con- 

 sistent with the trend toward transistor driven memory systems. 



By the use of a composite wire it should be possible to reduce the eddy 

 current losses and still preserve a reasonable wire diameter. A composite 

 wire, by definition, will consist of a non-magnetic inner wire clad with a 

 magnetic skin. It may be fabricated by a plating or an extruding process. 



The solid wire analysis of Section 3.1 is a special case of composite 



5 - 



O 



LU 

 CO 



z 



- 2 



3 - 



1 - 



10 15 20 25 



Haxial in OERSTEDS 



30 



35 



40 



Fig. 9 — Reciprocal of flux reversal time T s as a function of applied axial drive, 

 H , for solid and composite magnetic wires. Sufficient torsion applied to reach 

 saturation. 



