LNLS, Campinas, Brazil
Precision beamline systems, such as monochromators and mirrors, as well as sample stages and sample holders, may require fine thermal management to meet performance targets. Regarding the optical elements, the main aspects of interest include substrate integrity, in case of high power loads and densities; wavefront preservation, due to thermal distortions of the optical surfaces; and beam stability, related to thermal drift. Concerning the sample, nanometer positioning control, for example, may be affected by thermal drifts and the power management of some electrical elements. This work presents the temperature control architecture developed in house for precision elements at the first beamlines of Sirius, the 4th-generation light source at the Brazilian Synchrotron Light Laboratory (LNLS). Taking some optical components as case studies, the predictive thermal-model-based approach, the system identification techniques, the controller design workflow and the implementation in hardware are described, as well as the temperature stability results.
LNLS, Campinas, Brazil
TARUMÃ is the sub-microprobe station of the CARNAÚBA beamline at Sirius/LNLS*. Covering the range from 2.05 to 15keV, the probe consists of a fully-coherent monochromatic beam varying from 550 to 120nm with flux of up to 1e11ph/s/100mA after the achromatic focusing optics. Hence, positioning requirements span from nanometer-level errors for high-resolution experiments to fast continuous trajectories for high throughput, whereas a large flexibility is required for different sample setups and simultaneous multi-technique X-ray analyses, including tomography. To achieve this, the overall architecture of the station relies on a pragmatic sample positioning solution, with a rotation stage with a range of 220°, coarse stages for sub-micrometer resolution in a range of 20mm in XYZ and a fine piezo stage for nanometer resolution in a range of 0.3mm in XYZ. Typical scans consist of continuous raster 2D trajectories perpendicularly to the beam, over ranges that vary from tens to hundreds of micrometers, with acquisition times in range of milliseconds. Positioning is based on 4th order trajectories and feedforward, triggering includes the multiple detectors and data storage is addressed
* Geraldes, R.R., et al. ’Design and Commissioning of the TARUMÃ Station at the CARNAÚBA Beamline at Sirius/LNLS’ Proc. MEDSI20 (2020).