Beamline layout

Figure 1. Beamline layout of BL20U2

Soft X-rays are emitted from the light source - the undulator EPU60, and are reflected by a front deflection mirror SM1 to remove higher-order harmonics. After removing the thermal load, they pass through a white slit SLIT1 and enter a planar grating monochromator (PGM1). The grating monochromator consists of three variable line spacing and groove depth gratings with center line densities of 300L/mm, 800L/mm, and 1200L/mm, respectively, which can meet the requirements of energy resolution and flux for different energies. The deflection mirror SM3 behind the monochromator can switch light back and forth between the soft X-ray station and the soft-hard combi station. Subsequently monochromatic X-rays are focused vertically through the gratings on a monochromatic slit SLIT2, and after that pass through two sets of post focusing mirrors, a toroidal mirror (SM4) to focus on the elastic scattering station (REXS) sample position, and a KB mirror group (SM5/SM6) to focus on the inelastic scattering station (or emission spectrum station, RXES) sample points.