Design And Construction Of The Plane Grating Monochromators At Hefei Light Source

Synchrotron radiation-the radiation produced by a charged particle moving with relativistic speed in curved trajectories-is playing an increasingly important role in many areas of basic and applied sciences.Beamline,which bridges the light source and the experimental station,is one of the most important companents of the synchrotron radiation facility.It makes the whilte beam from light source to monochromatic one with certain photon energy,beam size,beam divergence and energy resolution.The core part of a beamline is monochromator,and in vacuum ultraviolet and soft x-ray wavelength range,the grating monochromators are common used,in which the plane grating monochromators play an important role beacause of the easily manufacture of the optical elements and the widely application fields.In this paper the characteristics of different kinds of plane grating monochromators are discussed and some relative key techniques are studied.Work of this paper is supported by the progress of upgrades of Hefei Light Source.The main contents are described in the following parts.In the first,characteristics of the two most popular plane grating monochromators,i.e.collimated-SX-700 plane monochromator and self-focus varied line spacing plane grating monochromator(SF-VLSPGM),are discussed in detail.Study found that the main energy resolution influencing factors of the two kinds of monochtomators are similar.However,because of the aberration correction function of the grating,the SF-VLSPGM contains less optical elements and can get longer incident and emergent arms than collimated-SX-700 one.So in condition of certain beamline length,SF-VLSPGM can get better energy resolution and better efficiency.But,the collimated-SX-700 monochromator also has some important advantages.It can work in different types,such as high resolution,high flux as well as high order suppression mode by adjusting the fix-focus constant.And it can also change the phase space of the spot at the exit slit.Work in this section will provide foundation for the design of similar beamlines.In the second,the optical design of the new soft x-ray microscopy beamline at Hefei Light Source is discribed.Performance of this beamline has a great improvement than before.The soft x-ray microscopy beamline,which ultilizes the radiation from a wiggler,covers the energy range from 200 eV to 2500 eV,with a collimated-SX-700 plane grating monochromator.This monochromator has two plane gratings with the line densities of 760 1/mm and 1400 1/mm respectively.The flux of the beamline at the endstation is better than 1×1012 phs/s with a 300 mA beam current.The resolution power is better than 500 @ 520 eV.The divergence angle at the exit slit is 2.6 mrad(H)x 2.8 mrad(V).In the third,the optical design of the combustion and flame beamline at Hefei Light Source is discribed.This beamline has an overall upgrade than the older one,and widely expands the use of synchrotron radiation in study of combustion and flame.The combustion and flame beamline ultilizes the radiation from an undulator and has a grazing incidence Czerny-Turner type plane grating monochromator,with a collimating toroidal mirror and a focusing toroidal mirror.It covers the energy range from 4.8 eV to 20 eV with two plane gratings,with the]ine densities of 200 l/mm and 400 l/mm respectively.The flux of the beam]ine at the endstation is better than 5×1012 phs/s with a 300 mA beam current.The energy resolution power is better than 3000 @ 15.8 eV.In the forth,the construction of the three new beamlines including the soft x-ray microscopy beamline(collimated-SX-700),the combustion and flame beamline(grazing incidence Czerny-Turner)and the catalysis and surface science beamline(SF-VLSPGM),are described in detail.The relative key techniques are studied,such as the test of the optical elements,precision slits,precision linear stages and the energy calibration of monochromator.The performance of the combustion beamline and the surface science beamline are tested,and the test results are close to the designed value.The operation energy resolution of the catalysis and surface science beamline is better than 10000@29.2 eV,and the performance reaches the advanced level of the international similar equipments.