on the Direct Current Corona. 



297 



from a bright reddish spot on the wire to a bright white 

 one on the tube. We may now speak of the negative 

 beads and perhaps the positive streamers as miniature or 

 beginning arcs which unite to form a single arc when the 

 current density reaches a certain value. 



The curve in fig. 10 will serve to show how the current 

 in the streamers increases with the time. At a potential 

 of 11,850 volts, somewhat above that for starting corona 



Fig. 11. 



ACCUMULATIVE IONIZATION 



• t 















3 





P 



■'essu 



-e 75 



L mm. 







Pi 1 













to 



a. 

 s 

 <6 





\ 



jTube 



ilfl£& 



1 









\ 













l 



o 



















\2 

 1 A 



Lr qu 



Tent 









A 







\ 









♦ 2 .4 



SPARK DISTANCE 



,6mm 



glow in air at 751 mm. pressure, a spark gap of 0-18 mm, 

 length was placed in series with the tube. Readings of 

 the current were taken at intervals of five seconds and 

 when plotted resulted in the given curve. An arc 

 passed shortly after 20 seconds but the maximum current 

 before it occurred was not obtained. 



The increase of the current depends largely on the 

 sparking distance and on the applied voltage (see curve 1 

 fig. 11). When the spark distance from zero is increased 

 the current for the positive streamers decreases at first 

 accompanied by a decreased brightness of the uniform 

 glow, reaches a minimum value, and as the streamers 



