Recent progress of the compact AFEL at Los Alamos

The Advanced Free Electron Laser (AFEL) is a compact, infrared, rf-linac FEL that uses a high-brightness photoinjector and a short-period permanent-magnet wiggler. Lasing at saturation with and without sidebands has been achieved over the 4--6 {mu}m region with a nominally 15-MeV electron beam energy and a 1-cmperiod, 24-period wiggler. Sideband-free FEL operation was optimized with respect to outcoupling by tuning off the reflectivity curve of the multilayer dielectric mirrors. Sideband operation was achieved using copper mirrors with a 1.1% outcoupling hole. The measured macropulse energy with {approximately}1300 micropulses was approximately 50 mJ per 1 nC of beam, corresponding to an output efficiency of 0.25% and a maximum extraction efficiency of 1.4%.