F. Cianciosi, A.-L. Buisson, P. Tafforeau, P. Van Vaerenbergh
ESRF, Grenoble, France
BM18 is an ESRF-EBS beamline for hierarchical tomography, it will combine sub-micron precision and the possibility to scan very large samples. The applications will include biomedical imaging, material sciences and cultural heritage. It will allow the complete scanning of a post-mortem human body at 25 µm, with the ability to zoom-in in any location to 0.7 µm. BM18 is exploiting the high-energy-coherence beam of the new EBS storage ring. The X-ray source is a short tripole wiggler that gives a 300mm-wide beam at the sample position placed 172m away from the source. Due to this beam size, nearly all of the instruments are devel-oped in-house. A new building was constructed to ac-commodate the largest synchrotron white-beam Experi-mental Hutch worldwide (42x5-6m). The main optical components are refractive lenses, slits, filters and a chop-per. There is no crystal monochromator present but the combination of the optical elements will provide high quality filtered white beams, as well as an inline mono-chromator system. The energy will span from 25 to 350 keV. The Experimental Hutch is connected by a 120m long UHV pipe with a large window at the end, followed by a last set of slits. The sample stage can position, rotate and monitor with sub-micron precision samples up to 2,5x0.6m (H x Diam.) and 300kg. The resulting machine is 4x3x5m and weighs 50 tons. The girder for detectors carries up to 9 detectors on individual 2-axis stages. It moves on air-pads on a precision marble floor up to 38m behind the sample stage to perform phase contrast imag-ing at a very high energy on large objects. The commissioning is scheduled for the beginning of 2022; the first ’friendly users’ are expected in March 2022 and the full operation will start in September 2022.
Front ends of the NSLS-II storage ring have numerous design requirements to ensure equipment and personal safety aspects of their designs. These design requirements, especially many pertaining to ray tracings, have gradually become overly stringent and a review is underway to simplify them for building future front ends. As a part of this effort we have assembled the front-end design requirements used in several other light sources. In this paper the assembled design requirements are discussed in comparison with those currently in use at NSLS-II.
Funding:This research benefited from a FRIA grant from the French Community of Belgium. With the growing number of fourth generation light sources, there is an increased need of fast positioning end-stations with nanometric precision. Such systems are usually including dedicated control strategies, and many factors may limit their performances. In order to design such complex systems in a predictive way, a mechatronic design approach also known as "model based design", may be utilized. In this paper, we present how this mechatronic design approach was used for the development of a nano-hexapod for the ESRF ID31 beamline. The chosen design approach consists of using models of the mechatronic system (including sensors, actuators and control strategies) to predict its behavior. Based on this behavior and closed-loop simulations, the elements that are limiting the performances can be identified and re-designed accordingly. This allows to make adequate choices concerning the design of the nano-hexapod and the overall mechatronic architecture early in the project and save precious time and resources. Several test benches were used to validate the models and to gain confidence on the predictability of the final system’s performances. Measured nano-hexapod’s dynamics was shown to be in very good agreement with the models. Further tests should be done in order to confirm that the performances of the system match the predicted one. The presented development approach is foreseen to be applied more frequently to future mechatronic system design at the ESRF.
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W.F. Sheng, H. Liang, Y.S. Lu, Z. Zhang
IHEP, Beijing, People’s Republic of China
Funding:This research is supported by National Natural Science Foundation of China (NSFC) (No.11905243). The stability of beamline optics directly affects the beamline’s performances, such as coherence, focal size, position stability of the beam and so on, it has become a serious issue for a low emittance 4th generation light source. The vibration transmitting function of supports plays a big role in the stability performance of the optics. In order to find out a stable supporting structure, several types of support structures were tested, and the transfer ratio were described. The result shows that wedge struc-tures generally have a lower transfer ratio, and point contact support structures should be avoided.
H. Liang, W.F. Sheng, H. Shi, Y.M. Yang, L.R. Zheng
IHEP, Beijing, People’s Republic of China
Funding:This research is supported by National Natural Science Foundation of China (NSFC) (No.11905243). The performance of monochromator is crucial to the performance of a beamline, especially for a 4th genera-tion synchrotron light source. To find out the perfor-mance of the monochromator prototype built for the HEPS project, it was tested at a wiggler beamline of BSRF with water cooling. The cooling of the crystals was measured by rocking curve broadening at different energy and cooling seems to be not enough due to indium foils. The repeatability in 1 hour was about 0.1 eV. The energy drift in 9 hours after the beam hit the beam-line was 0.4 eV at the Cu K edge. The short-term stability was tested with synchrotron beam under various cooling condition, and results between 4.4 nrad to around 400 nrad were observed. In conclusion, some performances are satisfying, but further improvements should be carried out in the future.
C. Muñoz Pequeño, J.M. Clement, P. Thevenau, P. Van Vaerenbergh
ESRF, Grenoble, France
This paper presents the design of a new linear fast shutter for topography and tomography. A prototype will be assembled and tested at the BM05 beamline at ESRF, and another unit will be installed in the future BEATS beamline at SESAME. The application of the shutter in X-ray diffraction topography allows performance of long exposure cycles of monochromatic beam on crystal samples while preventing irradiation of the detector during readout. It can be also used during sample alignment and acquisition of X-ray tomography scans. Particularly for white-beam tomography, which uses a very high photon flux, minimizing exposure is critical to protect the sample and detector from radiation damage. This highlights the importance of obtaining a short and uniform exposure time over the beam aperture. To fulfill this objective, a new shutter based on the synchronization of two tantalum blades driven by linear brushless DC motors is under development. This versatile design can be used with both monochromatic and white-beam, and it can achieve exposure times ranging from 50 ms to 60 s for a beam size of H 80 mm x V 20 mm. The linear motors allow for a much smoother operation, preventing vibration issues reported with the old shutter. In addition, the use of linear motors rather than solenoids allows an unlimited exposure time, where the previous version used solenoids that could overheat if kept open for too long. A test bench has been constructed for the characterization of the sequence produced by the linear motors, and exposure times of 50 ms with a maximum error of 1 ms have been measured. This article describes the main features of the shutter prototype and its associated motion control system, and the results of the measurements with the motor test bench are discussed as well.
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G. Iori, M.M. Al Shehab, M.A. Al-Najdawi, A. Lausi
SESAME, Allan, Jordan
M. Altissimo, I. Cudin
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Kaprolat, J. Reyes-Herrera, P. Van Vaerenbergh
ESRF, Grenoble, France
T. Kolodziej
NSRC SOLARIS, Kraków, Poland
Funding:EU H2020 framework programme for research and innovation. Grant agreement n°822535. The BEAmline for Tomography at SESAME (BEATS) will operate an X-rayμtomography station providing service to scientists from archaeology, cultural heritage, medicine, biology, material science and engineering, geology and environmental sciences*. BEATS will have a length of 45 m with a 3-pole-wiggler source (3 T peak magnetic field at 11 mm gap). Filtered white and monochromatic beam (8 keV to 50 keV, dE/E: 2% to 3% using a double-multilayer-monochromator) modalities will be available. In this work we present the beamline optical design, verified with simulation tools included in OASYS**. The calculated flux through 1 mm2 at the sample position will be as high as 8.5×109 Ph/s/mm2 in 0.1% of the source bandwidth, for a maximum usable beam size of 70×15 mm2. Beam transverse coherence will be limited to below 1 µm by the horizontal size of the X-ray source (~2 mm FWHM). For phase contrast applications requiring enhanced coherence, front end slits can be closed to 0.5 mm horizontally, with a reduction of the available beam size and photon flux. The BEATS beamline will fulfill the needs of the tomography community of SESAME. * H2020 project BEATS, Technical Design Report (July 2020). ** L. Rebuffi and M. Sanchez del Rio, Proc. SPIE 10388: 130080S (2017).
Tighter specifications in synchrotron instrumentation development force the design engineers more and more often to choose a mechatronics design approach. This includes actively controlled systems that need to be properly designed. The new Nano Active Stabilization System (NASS) for the ESRF beamline ID31 was designed with such an approach. We chose a multi-body design modelling approach for the development of the NASS end-station. Significance of such models depend strongly on its input and consideration of the right stiffness of the system’s components and subsystems. For that matter, we considered sub-components in the multi-body model as reduced order flexible bodies representing the component’s modal behaviour with reduced mass and stiffness matrices obtained from finite element analysis (FEA) models. These matrices were created from FEA models via modal reduction techniques, more specifically the component mode synthesis (CMS). This makes this design approach a combined multibody-FEA technique. We validated the technique with a test bench that confirmed the good modelling capabilities using reduced order flexible body models obtained from FEA for an amplified piezoelectric actuator (APA).
J. Reyes-Herrera, M. Sanchez del Rio
ESRF, Grenoble, France
The analysis of thermal stress of beamline components requires a comprehensive determination of the absorbed power profile. Consequently, accurate calculations of beam power density and its dependency on the photon energy are required. There exist precise tools to perform these calculations for undulator sources, like several methods available in the OASYS toolbox* considering, for example, the contribution of the different harmonics of the undulator radiation or using ray-tracing algorithms**. This is not the case for wiggler sources, in particular for short insertion devices that are used as source for the bending magnet beamlines in some upgraded storage rings like the ESRF-EBS. Wiggler radiation is incoherent and although it is possible the use of undulator methods for calculating it, this is very inefficient. In this work, we describe a tool that performs fast calculations of spectral power density from a wiggler source. The emission is calculated starting from a tabulated magnetic field and computes the power spatial and spectral density. It uses concepts inspired from Tanaka’s work***. It is implemented in a user-friendly widget in OASYS and can be connected to widgets to calculate absorbed and transmitted power density along the beamline components. The accuracy of the method is verified by calculating three examples and comparing the results with ray-tracing. The three insertion devices simulated are: the EBS-ESRF-3PW, the ESRF W150 (a high power wiggler) and the 3PW for the BEATS project at the SESAME synchrotron source. *L. Rebuffi, M. Sanchez del Rio, Proc. SPIE 10388: 130080S (2017). **L. Rebuffi et al., J Synchrotron Rad, 27, 1108-1120 (2020). ***T. Tanaka, H. Kitamura, AIP Conference Proceedings 705, 41 (2004).
