An X ray generator includes {HEAD ~ a cathode} having {TAIL ~ an emitter} made of carbon nanotubes which emits electrons by field emission and thus becomes a cold cathode electron emission source 
having
An X ray generator includes { HEAD ~ a cathode } having { TAIL ~ an emitter } made of carbon nanotubes which emits electrons by field emission and thus becomes a cold cathode electron emission source
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH