The construction of Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), a 0.1-nm hard X-ray free-electron laser (FEL) facility based on a 10-GeV S-band linear accelerator (LINAC), is achieved in Pohang, Korea by the end of 2016. The construction of the 1.11 km-long building was completed by the end of 2014, and the installation of the 10-GeV LINAC and undulators started in January 2015. The installation of the 10-GeV LINAC, together with the undulators and beamlines, was completed by the end of 2015. The commissioning began in April 2016, and the first lasing of the hard X-ray FEL line was achieved on 14 June 2016. The progress of the PAL-XFEL construction and its commission are reported here.

Pohang Accelerator Laboratory (PAL) have developed a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. At the first stage, PAL-XFEL needs two undulator lines for photon source. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator and soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. PAL have developed undulator magnetic structure based on EU-XFEL concepts. In this report, the impact of the background field, alignment issues, the results of pole height tuning, and final magnetic measurement results are summarized.

Characterizations of the high-density gas jets are performed for the laser–gas interaction. It is shown that the gas density profile can be obtained without the Abel inversion, when a Gaussian distribution is assumed. In addition, a rectangular nozzle is characterized for the long plasma generation. In this case, the Boltzmann distribution is introduced for the density profile and its result shows a good agreement with the experimental result.