Silent Electric Discharge 



83 



TABLE I.— VOLTAGE DISTRIBUTION BETWEEN ELECTRODES 



AND PLATE 



Table I shows the voltage characteristic for nitrogen which was 

 slightly contaminated. The low plate voltages which fell within the 

 range of one electroscope were due to contamination. 



It is unfortunate that we were unable to measure the total current 

 supplied to the needles and thus determine whether there was a large 

 increase in current when the voltage between the positive needle and 

 plate reached 24 kv. 



The large negative current at 44 kv. decreased very rapidly with 

 time as brought out by the curve of figure 7, but does not reverse. 

 However, at 55 kv. the current reversed very soon after the voltage 

 was applied and attained a very high positive value. 



The following factors may assist in the production of the phenom- 

 ena observed in the case of nitrogen: 



1. Electron emission from the zinc plate by postive ion bombardment. 



2. Ionization by collision with positive ions. 



3. The formation of large negative ions due to activation of the gas. 



4. Photoelectric effect produced by the action of the ultraviolet light 

 on the zinc plate. 



From the voltage data it would appear that numbers 1 and 2 were 

 the controlling factors, but they do not explain the initial voltage and 

 current characteristics found when the gas has previously been subjected 

 to the discharge. Evidently the gas undergoes a change, probably in the 

 positive discharge, from which, it does not recover for several hours. 

 The question of whether the molecules acquire the ability to pick up 

 electrons from the negative discharge and thus decrease their mobility 

 must be left for future investigation with high-voltage direct current. 



