A directly heated oxide cathode 1, wherein {HEAD ~ said core metal wire} comprises a tungsten core wire or {TAIL ~ a rhenium tungsten core wire} 
comprises
A directly heated oxide cathode 1 , wherein { HEAD ~ said core metal wire } comprises a tungsten core wire or { TAIL ~ a rhenium tungsten core wire }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL