The “Microfocus” beamline of SKIF storage ring is a multi-branch undulator beamline to be commissioned in 2024. The “in situ diffraction at extreme conditions” end-station is designed for X-ray diffraction (powder, single crystal, and multi-grain techniques) and total X-ray scattering from samples under high-pressure conditions (up to several million atmospheres) combined with high (up to 6000 K) and cryogenic temperatures. Extreme conditions will be achieved using diamond anvils cells (DACs) of various designs, as well as compact toroid (Paris-Edinburgh) presses. The end-station offers beam parameters suitable for solving the most demanding user tasks in the fields of Earth and planetary sciences, materials science, physics and chemistry of the extreme state of matter etc.
The section will use radiation of the 15th harmonic of superconducting undulator (resonance energy of 30.9 keV), with source dimensions (r.m.s.) of 9×8 μm, divergence of 16×13 mrad, and integrated flux of about 2×10^13 phot/s/0.1% b.w.
The “in situ diffraction at extreme conditions” end-station will consist of two experimental setups: a laser heating (LH) and general purpose (GP), where experiments can be carried out using DACs with resistive heating or cryogenic cooling, toroid press, etc.
To reach the smallest beam focus, a compound refractive lens (CRL) with ~1 m focal length will be placed in front of the sample, collecting a 10^10 phot/s flux into a 0.3×0.3 μm (FWHM) spot. A moderate focus mode using a pre-focusing CRL located in an optical hutch near the diamond monochromator will be also available. Using the pre-focusing CRL , almost the entire photon flux transmitted by the monochromator can be transported to the aperture of the focusing CRL. This configuration provide focusing of larger flux (10^11 phot/s) into a 1.6×1.4 μm spot (FWHM). The flux density in both modes is about 1011 ph/s/μm2, allowing the proposed scheme to compete with capabilities of similar beamlines of main world synchrotron facilities both in the tight focusing, and in flux density.
The reported study was funded by RFBR according to the research project #18-35-20047.