Multi-undulator spiral compact light source

A compact, small foot print, light source based on electron beam acceleration for insertion devices in EUV range metrology and actinic mask inspection using coherent scattering methods includes spiral storage rings providing plane straight sections. A magnet structure generates emittance for brilliance and coherent light content. A booster feeds the storage ring by top-up injection and keeps electron beam intensity stable. A booster level below the storage ring receives the electron beam from a linear accelerator in a central booster area. The source fits into laboratories or maintenance areas. Injection, RF-acceleration, beam manipulating devices and large diagnostics systems are required once. Higher average currents stored in the spiral enhance central cone power. Bunches are limited by ion trapping and a gap clears ions. The current is increased in the spiral. Gain in central cone power increases 5 fold, assuming a gap size of half single storage ring circumference.