Design of a high flux VUV beamline for low energy photons

A VUV beamline at the Shanghai Synchrotron Radiation Facility(SSRF) for angle-resolved photoelectron spectroscopy(ARPES) measurements is designed. To increase the resolution and bulk sensitivity, a photon energy as low as 7 e V is desired. Because the reflectivity for p-polarized photons strongly decreases when the photon energy is below 30 e V, the design of a high f lux beamline for low energy VUV photons is a challenge. This work shows a variable including angle Varied Line-space Plane-Grating Monochromator(VLPGM) with varied grating depth(VGD) which can achieve both high resolution and high flux with broad energy coverage.