I was wondering if you were seeking this term ->

CRT  - Catodhe Ray Tube  (they use CRT in TV sets and some CRT computers, today they are being replaced by LCD screens.) 

"ELECTRON GUN"

   Electrons guns is the "canhão de imagem" itself, but I think most of times one can use both, though meaning the other. I mean a CRT for the "canhão de imagem" in Brazil.

   Because the Electron Gun in itself is not that important, the whole system is; so a CRT may be what you were asking for...

   See some of these at:
http://content.answers.com/main/content/img/McGrawHill/Encyclopedia/images/CE114010FG0010.gif        or "electrons guns" here
http://www.jegsworks.com/Lessons/lesson5/crt.gif

http://www.cse.ohio-state.edu/~gurari/course/cis681/cis681Ch2.html

   Of course I was wrong as for Flybacks; in fact Flybacks [FBTs] are transformer used in CRTs.

Flyback Transformer (or FBT).   at     http://www.electronics-manufacturers.com/products/flyback-transformer-fbt-for-color-tv-computer-monitor-61.html
   and    http://www.a1articles.com/article_1268588_27.html

    Hope it clear it up now.        PP.