Optical Design for a Laboratory-Scale Compact Free Electron Laser based on Inverse Compton Scattering

Here we will report the design of an optical undulator and its impact on the design of a compact x-ray free electron laser (CXFEL). X-ray Free Electron Lasers (XFELs) are light sources characterized by high brightness, full spatial coherence, and short pulse durations, which enable experiments that probe materials at the time and length scales of electronic and structural motion. At Arizona State University, the Compact X-ray Free Electron Laser (CXFEL) will employ emittance exchange of a diffracted electron beam to seed an Inverse Compton Scattering (ICS)-based XFEL, which will generate fully coherent radiation with an accelerator length of 10 meters. By using an optical undulator (i.e. ICS), the electron beam energy requirements are lowered, and the facility size will be greatly reduced along with its cost. Tuning the crossing angle between the electron beam and ICS laser enables a higher electron beam energy, while lasing in the soft x-ray regime, which is necessary for minimizing the space-charge effects present in low-energy accelerators. We present an optical design optimized for generating 1 nm (1.2 keV) radiation with a 30 MeV electron beam at a 30 degree crossing angle using a 10 TW peak power drive laser, which is within reach of high repetition rate commercial laser sources.