A second hard X-ray beamline (HX2) at the PAL-XFEL (Pohang Accelerator Laboratory, X-ray Free Electron Laser) has been proposed to meet the increased demands of XFEL science. A photon energy ranging between 1.5 to 10 keV was determined to cover low photon energy with enhanced FEL pulse energy of about 3.0 mJ, and to cover mostly used range between 8 to 10 keV simultaneously. Accordingly, baseline design of the electron beamline was completed using MAD-X code. Here, to avoid physical overlap of the beamline elements, a dog-leg transport line is installed. In addition to first-order optics design, complete start-to-end simulation is performed to understand the evolution of the 6D electron beam phase space and to optimize the beam parameters such as energy chirp, energy spread, and emittance at the entrance of the undulator. In this study, we will show the start-to-end simulation by using Impact-T for injector section and ELEGANT for the remaining sections from linac modules to the end of the HX2 undulator line. Particularly, we will discuss whether coherent synchrotron radiation effects along the dog-leg section is suppressed so that the beam phase space distortion is minimized. Plus, we will introduce planned R&D activities such as AI/ML-based injector operation (virtual machine) and various studies on the XFEL modes such as multi-bunch operation, enhanced SASE (ESASE), and THz FEL.

The accelerator network of the Pohang Accelerator Laboratory (PAL) was initially designed and installed in 2015. It consists of three types of networks: a Public Network for external internet access, an Operation Network for accelerator operation and overall control, and a Control Network for device control and monitoring. From a hardware perspective, it comprises 2 firewalls, 1 intrusion prevention system, 4 backbones, 36 office network switches, and 77 switches for gallery and tunnel networks. Each network is physically or logically separated, and the backbone, serving as the main equipment, is configured in a redundant manner to prepare for failures

PAL-XFEL has achieved successful operation with both SASE and self-seeding modes. In an effort to broaden the capabilities of PAL-XFEL, research has been conducted on the generation of two-color XFEL pulses, leading to the development of two additional modes: two-color XFEL with time delay and pulse duration control, and time-synchronized two-color XFEL. In the first mode, a dipole magnet at the self-seeding section and a slotted foil at the bunch compressor are utilized. The pump and probe XFEL pulses are generated from undulators before and after the self-seeding section, respectively. The time delay between the pulses can be controlled using the dipole magnet, and the pulse duration can be manipulated using the triangular slotted foil. For the second mode, phase shifters are employed. Typically, phase shifters are used to optimize FEL intensity by matching the phase between the FEL pulse and the electron beam. However, by adjusting the phase shifter setting away from the matched condition, sideband spectra can be introduced, resulting in the generation of time-synchronized two-color XFEL pulses. The experimental results of these two additional modes will be presented.