The cantilevered, or similar, design is critical to provide {HEAD ~ the design} which allows for {TAIL ~ the separation} between the cathode and the insulator ring 
allows for
The cantilevered , or similar , design is critical to provide { HEAD ~ the design } which allows for { TAIL ~ the separation } between the cathode and the insulator ring
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH