Charged particle beam

1. unbunched beams, which have no longitudinal substructure in the direction of beam motion.
2. bunched beams, in which the particles are distributed into pulses of particles. Bunched beams are most common in modern facilities, since the most modern accelerator concepts require bunched beams for acceleration.

• the species of particle, e.g. electrons, protons, or atomic nuclei
• the mean energy of the particles, often expressed in electronvolts
• the particle current, often expressed in amperes
• the particle beam size, often using the so-called β-function
• the beam emittance, a measure of the area occupied by the beam in one of several phase spaces.

Common types

• Electron beam, or cathode ray, such as in a scanning electron microscope or in accelerators such as the Large Electron–Positron Collider or Synchrotron light sources.
• Proton beam, such as the beams used in proton therapy, at colliders such as the Tevatron and the Large Hadron Collider, or for proton beam writing in lithography.
• Ion beams, such as at the Relativistic Heavy Ion Collider or the under-construction Facility for Rare Isotope Beams.