How about some of the more antique and exotics, such as "Crookes tube" or
"Geissler tube"?
Yep, both of those asre 'tubes' in the UK
How about the "Electron Ray Tube" aka "Tuning Eye Tube" (6E5, EM81,
etc.)?
I think the official term is 'Electron Ray Tube' over here. The common
name is 'Magic Eye'.
-tony