560 Prof. K. T. Compton on Ionization and Production 

 Experimental Results. 



Figs. 2-5 show the results of several typical series of 

 measurements of the rate of charging of the electrode E as 

 a function of the accelerating difference of potential Y a at 

 various pressures p and for various thermionic currents I . 



Fig. 2. ^ = 00005 mm.; I 20 = l-75(10)"° amp. 



350 



300 



2 50 



^200 



2 E 



150 



100 



50 



==2 



EEEpEffi 



I . -a-^ CJL I I I ■ — — 



20 



22 



24 a/ 26 



28 



(Volts) 



30 



32 



2.00 



1.80 



R 



1.60 



1.40 



1.20 



1.00 



These thermionic currents I were determined by the filament 

 temperature, and are specified by I 20 , the total current to the 

 gauze G- with an accelerating field of 20 volts. To the 

 applied value of Y a there is to be added a small correction 

 due to initial velocity of emission, to contact difference of 

 potential between electrodes, and to the aggregate loss of 

 energy of the electrons due to the translator^ motion im- 

 parted to the helium atoms at the many elastic collisions*. The 

 correction due to the first two causes was not more than a 

 fraction of a volt, except when the tungsten was heated near 



* Benade and Compton, loc. cit. 



