Design of the PAL XFEL

The Pohang Accelerator Laboratory is going to build an X-ray free electron laser (FEL) based on self-amplified spontaneous emission (SASE). This new machine will utilize the existing 2.5-GeV injection linac to the storage ring by upgrading its energy up to 3.7 GeV or more. The target wavelength will be 3 - 4.5 angstrom, and its third harmonic 1 - 1.5 angstrom will also be used. The project will proceed in two stages: In the first stage, a vacuum-ultra-violet (VUV) SASE machine with 385 MeV will be constructed and tested for the proof of principle. The full X-ray machine will be constructed in the next stage. This paper describes the updated deign status of both machines.