Bigger Lenses, More Focus
Like the red-painted quadropoles, the green-painted sextupoles focus the electron beam. Each sextupole consists of six magnets, and more magnets means stronger focusing. As the electron beam travels down its path, it naturally spreads out; the magnets prevent that from happening by re-shaping the beam. In this image, the sextupoles wait on the sidelines to be installed in the beam line.
Image: Jefferson Laboratory