Funding:Ministry of Science, Technology and Innovation (MCTI) Next-generation nanoprobes, empowered by diffraction-limited storage rings, as Sirius/LNLS, present high-performance requirements aiming at high spatial resolution and throughput. For the focusing optics, this means assuring a small and non-astigmatic probe, high flux density, and remarkably high position stability, while also preserving beam wavefront. At stations further dedicated to spectromicroscopy and in-situ experiments, these requirements add up to having achromatic design and suitable working distance, respectively. In this way, Kirkpatrick-Baez (KB) mirrors have been chosen as the most appropriate solution for Sirius focusing optics. At TARUMÃ*, the first delivered nanoprobe at Sirius, the KB focuses the beam down to a 120 nm spot size (>8 keV) with a 440 mm working distance. This brought the requirements on the mirror’s angular stability to less than 10 nrad RMS, surface quality to single-digit nanometers, and alignment tolerances to the range of hundreds of nrad, which can be even tighter for other nanoprobes. Such specifications are particularly challenging regarding clamping, vibration, and thermal expansion budgets, even testing optical metrology limits during alignment and validation phases. The resulting KB mechanism is an opto-mechanical system with an exactly-constrained, deterministic design**, and suspension modes well above 250 Hz, sufficiently coupling optics to sample in the same 6-DoF base. It provides low-order aberration corrections by single degree-of-freedom alignment with piezo actuators, while higher order aberrations from clamping and thermal deformations are mitigated by gluing each mirror to flexure-based mounting frames. This contribution presents the design, assembly, and commissioning of the KB system at TARUMÃ as a reference case. *Tolentino, H.C.N., et al. "TARUMÃ station for the CARNAÚBA beamline at SIRIUS/LNLS" SPIE 11112 19 **Geraldes, R.R., et al. "The Design of Exactly-constrained X-ray Mirror Systems for Sirius." MEDSI18
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Development of a Passive Tuned Mass Damper for Ultra-High Vacuum Beamline Optics
115
F. Khan, D. Crivelli, J.H. Kelly, A. Male
DLS, Oxfordshire, United Kingdom
Vibration in beamline optics can degrade the quality of experiments: the resulting movement of a mirror increases the x-ray beam position uncertainty, and introduces flux variations at the sample. This is normally dealt with by averaging data collection over longer periods of time, by slowing down the data acquisition rates, or by accepting lower quality / blurred images. With the development of faster camera technology and smaller beam sizes in next generation synchrotron upgrades, older optics designs can become less suitable, but still very expensive to redesign. Mechanically, mirror actuation systems need to be a balance between repeatability of motion and stability. This normally leads to designs that are ’soft’ and have resonant modes at a relatively low frequency, which can be easily excited by external disturbances such as ground vibration and local noise. In ultra-high vacuum applications the damping is naturally very low, and the amplification of vibration at resonance tends to be very high. At Diamond we designed a process for passively damping beamline mirror optics. First, we analyse the mirror’s vibration modes using experimental modal analysis; we then determine the tuned mass damper parameters using mathematical and dynamic models. Finally, we design a flexure-based metal tuned mass damper which relies on eddy current damping through magnets and a conductor plate. The tuned mass damper can be retrofitted to existing optics using a clamping system that requires no modification to the existing system. In this conference paper we show a case study on a mirror optic on Diamond Light Source’s small molecule single crystal diffraction beamline, I19.
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Ultra-Precision Mechanics for Fourth-Generation Sources
R. Doehrmann, S. Botta, P. Wiljes
DESY, Hamburg, Germany
Fourth-generation synchrotrons, with their extremely good beam conditions, offer experimental possibilities that go far beyond the current technological state of the art. These extremely brilliant x-ray sources enable, among other things with new focusing optics, focal sizes in the nanometer range with the highest intensity and thus allow for highly dynamic experiments also on this scale. In order to guarantee the required beam quality all the way down to the experiment, optimal conditions must be generated for the end stations and for the beamline optics. An optimum of stability and precision can unfortunately only be achieved if, on the one hand, the infrastructure that shields the experiments and enables undisrupted operation is planned very carefully. On the other hand, the scientific instruments must also be optimized and improved. Our strategy for the construction of the PETRA IV experiments is based on five pillars (low vibration, stable environment, rigid construction, optimized design and fast feedback). In this contribution, we describe these concepts in more detail. Furthermore, we present illustrative examples of a possible implementation at PETRA IV.
Investigations on Stability Performance of Beamline Optics Supports at BSRF
125
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.Y. He, L. Kang, L. Liu, R.H. Liu, X.J. Nie, A.X. Wang, L.Q. Zhao
IHEP, Beijing, People’s Republic of China
The construction of the South Advanced Light Source Platform will be completed in 2021. Among them, the high-precision test hall requires that the effective value of the micro-vibration of the foundation be controlled within the vibration range of 25nm, which has already met the requirements of nanometer level. Research at dongguan machinery group, therefore, in view of the high precision testing hall, south of advanced light source is proposed to geological environment factors, carry out detailed geological survey measurement, focus on the advanced light source foundation vibration test, resistance to vibration and vibration characteristics research foundation and anti-vibration scheme research and the advanced light source is the key equipment vibration reduction technology research, through to the light source address of the proposed foundation vibration test, the vibration of foundation design, synchrotron radiation device key equipment comprehensive analysis and research of vibration reduction technology, formed a series of foundation vibration and key equipment solution, for the later construction of the southern light source to lay a solid foundation.
Study the Active Vibration Control System of the Parallel 6-DOF Platform
131
R.H. Liu, H.Y. He, Z.Y. Ke, L. Liu, X.J. Nie, C.J. Ning, A.X. Wang, Y.J. Yu, D.H. Zhu
IHEP CSNS, Guangdong Province, People’s Republic of China
L. Kang, J.S. Zhang
IHEP, Beijing, People’s Republic of China
G.Y. Wang
Institute of High Energy Physics, CAS, Guangdong, People’s Republic of China
Funding:National Natural Science Foundation of China 11905231 With the development of high-energy synchrotron radiation light source with high energy, high brightness, low emittance and nano-scale light spot, accelerators and beamline stations have higher requirements for the stability of the system, and active vibration isolation technology has been paid more and more attention. It has become the key technology for the development of major scientific devices (such as high-energy synchrotron radiation light source, free electron laser, etc.) in the future. In this paper, an active vibration control system driven by piezoelectric ceramic actuator with strong adaptability is designed. NI Compact-RIO real-time control system and Fx-LMS adaptive filter control algorithm are used for the active vibration control system. The identification method of input and output channels and the active control module are simulated by MATLAB. And an active vibration control system based on a parallel 6-DOF platform was built for experimental verification. The experimental results show that the designed active vibration control system has a good control effect for low-frequency micro-vibration.
Ground Vibration Measurements and Analysis for the SHINE Project
F. Liu, Z. Wang
ShanghaiTech University, Shanghai, People’s Republic of China
R. Deng, N. Mao, L. Zhang, W. Zhu
SARI-CAS, Pudong, Shanghai, People’s Republic of China
Y. Liu
Shanghai Institute of Optics and Fine Mechanics, Shanghai, People’s Republic of China
Funding:Precision Adjustments for High Stability and High Heat load Mirrors. Plan for Science and Technology innovation of Shanghai. No. 19142202800 The Shanghai HIgh repetitioN rate XFEL and Extreme light facility (SHINE) is the first hard X ray free electron laser facility in China. The facility is located in Zhanghai HighTech Park in Shanghai, with a total length of 3.1 km, consisting of three tunnels which are around 29 meters underground and 5 shafts. The 1st shaft is for injection, the 2nd shaft is for electron switches, the 3rd shaft is for beam dumps, the 4th shaft is the near experimental hall, while the 5th shaft is the far experimental hall. As such a long facility, the stability caused by the environmental vibrations is always a big concern. In this report, several vibration sensors, including accelerometers, seismometers, and velocity sensors were compared to find out the frequency range of the sensors. The vibration on the ground of the 1st shaft as well as underground were measured and analyzed. Furthermore, the ground vibrations were also compared with SSRF and SULF. To investigate the ground vibration effect on the beam transportation, the real vibration PSDs were imported into finite element analysis (FEA) model for random vibration analysis, the angular vibrations of the model were analyzed and tested.
One of the most challenging problems for experimental setups at third-generation and especially fourth-generation synchrotrons are vibrations. In order to keep vibrations on a as low as possible level one must not only take extremely care in the design of all components but also have a profound knowledge of the sources of vibrations. We started a project to map the vibrations at PETRA III both locally and timely in order to get a better understanding of the influencing factors and possible consequences for the ongoing PETRA IV project. In this contribution we will report on our first results of this project.
Bringing the Ground Up (When Is Two Less Than One?)
182
A.A. Khan, C.A. Preissner
ANL, Lemont, Illinois, USA
Funding:Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility, operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The Advanced Photon Source Upgrade project has employed the use of high heat load dual mirror systems in the new feature beamlines being built. Due to the shallow operating angles of the mirrors at a particular beamline, XPCS, the two mirrors needed to be approximately 2.5 m apart to create a distinct offset. Two separate mirror tanks are used for this system. However, it is unclear if the vibrational performance of these tanks would be better if they were both mounted on one large plinth or each mounted on a small plinth. Using accelerometers at the installation location, the floor vibrations were measured. The resulting frequency response function was then imported into a Finite Element Analysis software to generate a harmonic response analysis. The two different plinth schemes were modeled and the floor vibration was introduced as an excitation to the analysis. The relative pitch angle (THETA Y) between the mirrors was evaluated as well as the relative gap between the mirrors (XMAG). Results showed that a single plinth reduces the relative XMAG (RMS) compared to two plinths by approximately 25%. However, the relative THETA Y (RMS), which is arguably more critical, is significantly lower by approximately 99.7% in two plinths when compared to a single plinth. Therefore, it is more effective to use two separate plinths over a longer distance as opposed to a single longer granite plinth.
