Electron gun

A repulsive ring placed between the electrodes focuses the electrons onto a small spot on the anode, at the expense of a lower extraction field strength on the cathode surface.

Photoinjectors play a leading role in X-ray Free-electron lasers and small beam emittance accelerator physics facilities.

The most common use of electron guns is in cathode-ray tubes, which were widely used in computer and television monitors before the advent of flat screen displays.

Each stream travels through a shadow mask where the electrons will impinge upon either a red, green or blue phosphor to light up a color pixel on the screen.

This technology is sometimes used in mass spectrometry in a process called electron ionization to ionize vaporized or gaseous particles.