Accelerator Based X-ray Sources Carrying Orbital Angular Momentum

The characteristic of vortex beam with orbital angular momentum(OAM)is that the phase structures rotate when they propagate through space,which has phase singu-larity,and each photon has an OAM of lh.Optical vortex with OAM has been widely used in micro manipulation,micro-machining,imaging,communication,quantum en-tanglement and so onWith the rapid development of the fourth generation of light source-X-ray free-electron lasers(FELs),this kind of X-ray,which has the properties of super peak bright-ness,ultrashort pulse and excellent coherence,can be used to detect the structure of matter in ultra-small(nm)and ultrafast time(fs).In addition,it plays an irreplaceable important role in atomic and molecular physics,condensed matter physics,structural biology,surface catalysis and ultrafast chemistry and material scienceIn recent years,X-ray carrying OAM has become a hot research topic in the world It can be used in diffraction imaging,ultrafast magnetisms,X-ray orbital circular chro-matography and so onTherefore,we propose a scheme to generate XOAM based on the Shanghai Soft X-ray FEL(SXFEL).The innovative points of this scheme are as follows:1.According to the existing methods of OAM generation,the most suitable method for SXFEL to gen-erate XOAM is analyzed and summarized;2.A method of directly adding two-segment helical undulator to the end of SASE device at SXFEL to generate XOAM is firstly sim-ulated;3.Using this scheme,we can generate high-energy XOAM rays(wavelength is about?1 nm)for studying the magnetic structure size of magnetic materials.In the process of scheme design,we summarize the methods of generating XOAM,and deeply study the theoretical process of this scheme.Through the simulation calculation,we get the XOAM with good stability and wavelength of?1 nmIn order to miniaturize the device and generate high-energy XOAM in the lab-oratory,we use the Laser Compton Scattering(LCS)method,and study the nonlinear process of LCS when the circularly polarized laser collides with the relativistic electron Through theoretical analysis and simulation calculation,we obtain the X-ray vortex light of the order of keV.It provides the possibility for the future laboratory to carry out the scientific application of high energy X/y ray vortex light.