Experimental Technique

Wavefront sensing, Reflectivity, Ptychography, High energy resolution measurement (Mach-Zehnder interferometer), SR thermal power measurement, visible light measurement for mirror under thermal condition

The TEST beamline is dedicated to the in-house research for soft X-ray optics and SR instrumentation. It can also support detector calibration and early-stage tests for advanced experimental techniques. Currently, one of the beamline endstations supports a new experimental technique using ptychography for quantum materials research.

Beamline optics

Overview

The beamline is sourced by a linear polarization undulator (LPU38). It has two branches, namely, the mono beam branch and the white/pink beam branch. The mono beam branch uses the cPGM layout, has two gratings with energy resolving power of 100k @400 eV and 5k @ 867 eV. Endstation 3 at the end of the mono branch holds the Mach-Zehnder interferometer used to measure the ultra high-energy resolving power from the monochromator. It also supports the ptychographic characterization of quantum materials. The white/pink beam branch holds two endstations. One is for thermal management research on SR instrumentation, the other is for soft X-ray optics research. The beam directly from the source incident on the endstation for thermal management research. It then goes through a heat load chopper and two harmonic rejection mirrors before it reaches the endstation for X-ray optics research. The beam (ranging from 250 eV to 1000 eV) with the intrinsic bandwidth is used for this endstation. 

Endstation for thermal management research

Overview

The endstation for thermal management research aims to support the thermal management for the in-houses development of SR instrumentation. It provides various sensors and detectors to probe the behaviour of the optical element (mainly mirror) with the shine of white beam. Visible light interferometer is placed outside the chamber to detector the change of the surface topography, infrared camera is used to monitor the temperature on the optical surface. An in-house developed thermal power meter is also installed to measure the direct and reflected thermal power from the source.  

Key Equipment

Endstation for X-ray optics research

Overview

The endstation for X-ray optics research receives the attenuated and filtered fundamental-energy beam for in-house soft X-ray optics research. The beam is attenuated by a heat load chopper. The harmonic rejection mirrors absorb the higher harmonic beam as well as attenuate the incident beam. The endstation works on the fundamental energy ranging from 250 eV to 1000 eV. The bandwidth is the intrinsic value (~1%) from the LPU38. 

Key Parameters

Mach-Zehnder interferometer

Overview

The Mach-Zehnder interferometer is placed after the slit (~64 m) for the mono beam. Its main task is to measure the high energy resolving power from the grating monochromator. 

Key Parameters

Science

Scientific Scope 1： The TEST beamline aims to support the in-house development of SR instrumentation. The endstation for thermal management research is built to investigate the cooling schemes for the optical elements. It can help to tackle the ever-increasing thermal problem when the storage ring goes to diffraction-limited. The endstation for X-ray optics research provides an experimental chamber to test the in-house developed instrument, such as the bending mirror. By combining the various wavefront sensing techniques, we can obtain the online and at-wavelength feedback for the test of the instrumentation. 

Scientific Scope 2： The other focus for the TEST beamline is to support the research on soft X-ray optics. The endstation for X-ray optics research is dedicated to this. It provides an experimental chamber to develop the various wavefront sensing techniques. By using these techniques helps to devise all kinds of schemes for wavefront correction. The novel optics designed for advanced experimental methods can also be tested in this beamline.

People

Useful Link

Related beamlines:

TEST beamlines:

https://ssrf.sari.ac.cn/dkxzz/tbfs/gsxz_gb/xzdl_tbfs/bl09b/xzjs/

https://english.ihep.cas.cn/heps/fa/bl/202112/t20211222_295080.html