A hollow tube anode current collector is sealed to {TAIL ~ a glass ring} which is sealed to {HEAD ~ a metal outer ring} 
A hollow tube anode current collector is sealed to { TAIL ~ a glass ring } which is sealed to { HEAD ~ a metal outer ring }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD