Development of fast x-ray imaging beamline at SSRF

The X-ray fast imaging beamline at SSRF is a new beamline under construction and will provide X-ray micro-imaging on multiple time-scale from 100 ps, s and ms to study the following fast processes such as deformations and invalidations of materials under strong dynamic load and the high pressure/speed spray process of fuel in automobile engines. The beamline will have the capability of about 100 ps temporal resolution and micrometer scale spatial resolution. Including the researches of dynamic impact of materials, high speed fluid dynamics and the calibration of the streak camera could be done on this beamline. In addition, X-ray dynamic micro-CT is also available on the beamline, which is a powerful tool for the researches of the deformation mechanism in the invalidation dynamics processes of light-weight high-strength alloys and the formation mechanism of the defects in the solidification processes of these alloys. Using the dynamic micro-CT technique, the research of soft matter system including granule, foam and colloid also could be carried out to establish the links between its microscopic structure, kinematics and macroscopic appearance. A cryogenic permanent magnet undulator (CPMU) cooled by liquid nitrogen will be selected as the light source providing the X-ray photons with energy range of 8.7-30 keV, whose smallest magnet gap is 6 mm. With the periodic length of 18mm and 170 periods, the total length of the undulator is 3.06 m. The beamline will provide pink beam mode and monochromatic beam mode with a liquid nitrogen cooled double-crystal monochromator. The first crystal of DCM can be moved in or out of the beam, making the monochromatic or pink beam available. For the fast imaging, a millisecond-shutter (water cooled) and a microsecond-shutter are used to control the exposure time of imaging detectors and reduce unwanted heat of the pink beam. The experimental endstation will provide multiple X-ray imaging detectors to meet the different requirements of spatial and temporal resolution. In-situ devices include small gas gun, compression/tension Hopkinson bar, high speed spray set-up, furnace with electric/magnetic field and stretching devices. Up to now, the construction of the beamline and two-turn small beam current commissioning has been completed. The test results show the the design technical indexes have been reached. The beamline will be in test operation in 2022.