In accelerator physics, a beamline refers to the trajectory of the beam of accelerated particles, including the overall construction of the path segment (vacuum tube, magnets, diagnostic devices) along a specific path of an accelerator facility. This part is either

• the line in a linear accelerator along which a beam of particles travels, or
• the path leading from a cyclic accelerator to the experimental endstation (as in synchrotron light sources or cyclotrons).