TV cathode ray tube. Components of a cathode ray tube (CRT) display for a television (TV). These are the components that are behind a TV screen. At upper centre is the electron gun, surrounded by electronics. The electron gun produces a beam of electrons (also called a cathode ray because it is produced by heating of a cathode). This beam of electrons is directed through a set of magnetic coils (lower centre, yellow) towards the screen (not seen, off bottom). The magnetic field from the coils is varied to deflect the electron beam as required. The beam is moved across the screen, triggering the release of light from the phosphor materials on the inside of the screen. This produces the images seen on a TV screen.