electron gun

An electron gun is a part of cathode ray tube on increasing the filament current the rate of emission of electrons from the cathode will increase. on the other hand, by increasing the accelerating potential on anode, the energy of electrons reaching the anode will increase due which the electrons will strike the screen with a greater speed.

It is a device that directs a steady stream of electrons in a desired direction,
e.g. in a cathode-ray tube

Cathode ray tube works on the principle of (i) thermionic emission (ii) deflection of electron beam by the electric and magnetic fields and(iii) flourescence produced by the electron beam on the flourescent screen.

The cathode ray tube (CRT) is a vacuum tube containing an electron gun and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to form images in the form of light emitted from the fluorescent screen. The image may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets and others.