Radiation emitted by the cathode of a thermionic electron valve containing a gas at low pressure. In 1897 J. J. Thomson
identified the rays as streams of charged, elementary particles having extremely low mass, later called electrons
. Some electrons are emitted because the cathode
is heated but most because of collisions between the cathode and positive ions formed in the valve.
cath·ode-ray tube (abbr.: CRT) (also cath·ode ray tube) •
n. a high-vacuum tube in which cathode rays produce a luminous image on a fluorescent screen, used chiefly in televisions and computer terminals.
Evacuated electron tube used for television picture tubes, oscilloscopes and display screens in radar sets and computers. An electron gun shoots a beam of electrons, focused by a grid. The electrons strike a fluorescent screen and produce a spot of light. In a television tube, an electrostatic or magnetic field deflects the beam so that it scans a number of lines on the screen, controlled by the incoming picture signals.
cath·ode ray •
n. a beam of electrons emitted from the cathode of a high-vacuum tube.