ABSTRACTS OF TECHNICAL ARTICLES 259 



An Improved Electrolysis Switch. V. B. Pike^ Corrosion, 8, pp. 311- 

 313; disc. pp. 322-323, September, 1952. (Monograph 2021). 



An improved electrolysis switch has been placed in use in the Bell System for 

 mitigation of electrolysis of cables by stray currents. It consists of three relays 

 operating in sequence, namely control, intermediate and drain relays. It auto- 

 maticalh^ closes a drainage bond between a lead-covered underground cable and 

 a power return ground when stray current is picked up by the cable to such 

 an extent as to make some of the sheath positive with respect to its environment. 

 It also opens bond when the drainage current falls to zero and drainage is no 

 longer required. Two sizes are used capable of draining 200 amperes and 400 am- 

 peres, respectively. Its action is very fast, only 0.015 second elapsing from the 

 time the control circuit releases until opening of the drainage bond. Separate ad- 

 justments are available for setting the voltage at which the switch closes and 

 opens the drainage bond. A capacitive voltage booster enables switch operation 

 over longer battery power supply wires than is possible if the booster is not used. 

 A power supply unit consisting of a stepdown transformer and selenium rectifier 

 is also available to operate the switch with power drawn from an AC power 

 source if the switch must be installed beyond reach of the battery power. A sealed 

 steel housing enables the switch to withstand submersion and permits installation 

 in very damp locations. 



Statistics of the Recombinations of Holes and Electrons. W. Shockley* 

 and W. T. Read, Jr.^. Phijs. Rev., 87, pp. 835-842, September 1, 1952. 

 (Monograph 2022). 



The statistics of the recombination of holes and electrons in semiconductors is 

 analyzed on the basis of a model in which the recombination occurs through the 

 mechanism of trapping. A trap is assumed to have an energy level in the energy 

 gap so that its charge may have either of two values differing by one electronic 

 charge. The dependence of lifetime of injected carriers upon initial conductivity 

 and upon injected carrier densit}' is discussed. 



Motiort, of Gaseous Ions in a Strong Electric Field. G. H. Wannier^ 

 Phys. Rev., 87, pp. 795-798, September 1, 1952. (Monoj;raph 2023). 



This paper continues an earlier one on the same subject. Its object is to eluci- 

 date the nature of the random motion of an ion about its drift. In Section F it is 

 shown that this motion can be described as a diffusion with a diffusion tensor 

 axially symmetric about the field. If the mean free time between the collisions of 

 an ion with molecules is independent of speed, then explicit expressions may be 

 deprived for the two diffusion coefficients; these expressions are written down 

 without proof in Section G; they are connected with the mobility by a natural 

 extension of the Einstein relation. In Section H, the longitudinal diffusion co- 

 efficient is computed numerically for the hard sphere model, high field, and mass 

 ratio 1; the method of computation is the same as in Section D. Finally, it is 

 shown in Section I how approximate formulas of wider validity can be inferred 

 from the ones obtained. 



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