First lasing of the Jefferson Lab IR Demo FEL

As reported in previous work (Neil, Proceedings of the 1998 European Partic le Accelerator Conference, Stockholm, Sweden, 1998, p. 88; Shinn, in: Free- Electron Laser Challenges, Proceedings of SPIE, vol. 2988, 1997, p. 170), J efferson Lab is building a free-electron laser capable of generating a cont inuous wave kilowatt laser beam. The driver-accelerator consists of a super conducting, energy-recovery accelerator. The initial stage of the program w as to produce over 100 W of average power with no recirculation. In order t o provide maximum gain the initial wavelength was chosen to be 5 mu m and t he initial beam energy was chosen to be 38.5 MeV. On June 17. 1998, the las er produced 155 W cw power at the laser output with a 98% reflective output coupler. On July 28th, 311 W cw power was obtained using a 90% reflective output coupler. A summary of the commissioning activities to date as well a s some novel lasing results will be summarized in this paper. Present work is concentrated on optimizing lasing at 5 mu m, obtaining lasing at 3 mu m, and commissioning the recirculation transport in preparation for kilowatt lasing this fall. (C) 1999 Elsevier Science B.V. All rights reserved.