Electron beam

shaft of electrons moving at high speed in the same direction

Cathode rays are streams of electrons observed in vacuum tubes, i.e. evacuated glass tubes that are equipped with at least two electrodes, a cathode (negative electrode) and an anode (positive electrode) in a configuration known as a diode.When the cathode is heated, it emits radiation which travels to the anode. If the inner glass walls behind the anode are coated with a phosphorescent material, they glow. A metal shape placed between the electrodes casts a shadow on the glowing coating. This suggests that the cause of the light emission was composed of rays emitted by the cathode and hitting the coating. They travel towards the anode in straight lines and continue past it for some distance.
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Noun
1. a group of nearly parallel lines of electromagnetic radiation
(synonym) beam, ray
(hypernym) electromagnetic radiation, electromagnetic wave, nonparticulate radiation
(hyponym) cathode ray

A stream of electrons (small negatively charged particles found in atoms) that can be used for radiation therapy.

a focused stream of electrons.

see Electron Beam.