208 Mr. M. Ishinocm Velocity of Secondary Cathode Rays 



Thus the initial velocity of the positive ions should be very- 

 small. Hence it was expected that the positive ions would 

 not affect the measurement of the distribution of velocities 

 of the secondary cathode rays. Measurements have been 

 carried out with two gauzes. To them the following poten- 

 tials were applied: Vx = 0, V 2 =— v volts, where v was 

 varied from to several hundred volts. The currents 

 arriving at the electrometer-electrode were measured. The 

 results are shown in nV. 2. 



1%. 2. 



sj/o/\ ui/\ 



Vin Vo/ts 



The form of the curve shows that ionization occurred for 

 large values of v. This ionization should be attributed to 

 the positive ions, because almost all the negative corpuscles 

 must be stopped at the gauze V 2 by such high potentials. 

 But the positive ions, diffusing into the region between V! 

 and V 2 , are accelerated there, and get a velocity high enough 

 to be able to ionize the residual gas ; and the corpuscles thus 

 produced are driven to the electrode E by the electric force 

 between V 2 and E. Using different fields, such as Vi= — 10 



