SPARK GAP SWITCHES FOR RADAR 



565 



dielectric strength of air, sparking failed to take place a large fraction of 

 the time. 



O 4000 



600X 10'^ 

 TIME IN SECONDS 



(b) 



TIME IN SECONDS 

 (C) ' 



Fig. 1 — (a) Line modulator circuit with rotary spark gap switch, (b) switch voltage 

 vs. time, (c) maximum voltage gradient between electrodes vs. time. 



Experiment indicated that this was caused by spark delay time, as 

 irradiation of the cathodes by means of an ultra-violet lamp produced 100% 



