<p>Multiple ion source designs that appear radically different have evolved from an azimuthal magnetic cusp layout developed for fusion Neutral Beam Injectors (NBI). The ion sources of the iG series of flat panel implanters are a direct descendant of the original NBI source. Another large area NBI ion source, CLPS, and a very small plasma flood, HD PFS, benefitted from a magnetic gradient enhancement, but a familial magnetic theme is not obvious. Most of the magnets in the CLPS are arranged in an axial cusp, and the HD PFS uses just a single magnet. However, all three designs critically rely on a global azimuthal cusp topology. We will describe in detail the development of these plasma sources and show how common magnetic design criteria proved critical to their commercial success.</p> Graphical Abstract <p></p>