SPARK GAP SWITCHES FOR RADAR 



573 



operated successfully for somewhat over 100 hours before enough scattered 

 material accumulated to interfere with gap insulation. A uniform spark 

 distribution was maintained throughout this time and measurement showed 

 that aluminum was removed quite uniformly from the raised portion of the 

 cathode to a depth of only a fraction of a millimeter. An equally thick 



Fig. 6 — Three gap tube having aluminuni clcclrocks and a li\tlrugcn argon atmosphere 

 — actual size. 



though somewhat rougher deposit was formed on the Opposing anode surface, 

 thereby retaining the gap spacing very satisfactorily. About 30 milligrams 

 of loose material were scattered throughout the tube. 



A more drastic but also more successful design change was introduced by 

 making three separately enclosed gaps, one of which is shown in the photo- 



