Guiding and focusing the particles

Using electromagnetic forces

Electric forces: are used to accelerate the charged particles (protons, electrons, ions, …) within cyclotrons.
Magnetic forces: are specifically used to guide these particles along around bends corners in the accelerator, and are generated by electromagnets. These dipoles select particles according to their velocity or mass.

Quadrupoles for focusing

Between the consecutive accelerators, the particles move within tubes. Since ions are electrically charged, and tend to move apart. Therefore, their trajectories are not straight, and the beam diameter increases continuously like a light spectrum.

Special magnets, the quadrupoles, are used to focus the particles.

Pumps continuously extract air from within these tubes to produce a high vacuum, so that the accelerated particles do not interact with the air's atoms. The pressure is approximately 10 billion times smaller than atmospheric pressure.