Abstracts of Technical Articles from Bell System Sources. 



The Effect of Temperature on the Emission of Electron Field Currents 

 from Tungsten and Molybdenum} A. J. Ahicakn. Electron field 

 currents from the central portion of long molybdenum and tungsten 

 filaments about 2.7 X 10~^ cm. in diameter have been studied. The 

 field currents were first made stable to about 5 per cent by long- 

 continued conditioning treatments of temperature and high voltage 

 under high vacuum conditions. Thermionic emission measurements 

 gave the values 4.32 and 4.58 volts for the work function of the 

 molybdenum and tungsten, respectively, in good agreement with 

 the accepted values for the clean metals. Emission measurements 

 were then made at fields varying from about 5 X 10-^ volts/cm. to 

 about 1 X lO*' volts/cm. and at temperatures varying from 300° K. 

 to about 2000° K. Down to about 1600° K. the thermionic currents 

 completely masked the field currents. Thermionic emission values 

 below 1600° K. were obtained by extrapolation. Thus the field 

 currents at the lower temperatures were separated from the thermionic 

 currents. Where necessary, corrections were made for the decrease 

 in the voltage gradient accompanying the thermal expansion of the 

 filament. The field currents were found to be independent of tem- 

 perature to within 5 per cent from 300° K. to 1400° K. At tempera- 

 tures higher than 1400° K. the data are consistent with the assumption 

 that the current consists of a thermionic current plus a current which 

 is independent of temperature. However, because of the exponential 

 change of thermionic current with temperature a small effect of tem- 

 perature on the field current could not be distinguished at temperatures 

 higher than 1400° K. From the theory of Fowler and Nordheim, /3, 

 a factor introduced by surface irregularities, is found to be 120 for 

 the tungsten cathode and 47 for the molybdenum one. Thus for 

 tungsten, Houston's theory of the temperature effect is in approximate 

 agreement with the negative results of these experiments. 



Measurement of Transmission Loss Through Partition Walls." E. H. 

 Bedell and K. D. Swartzel, Jr. This paper reviews the theory and 

 describes the method used at Bell Telephone Laboratories of measuring 

 the transmission loss through partition walls. The partition to be 



1 Phys. Rev., August 15, 1933. 



2 Jour. Acous. Soc. Amer., July, 1933. 



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