C.S.N.C. Bueno, F.A. Borges, G.R.B. Ferreira, R.R. Geraldes, L.M. Kofukuda, M.A.L. Moraes, G.B.Z.L. Moreno, D.V. Rocha e Silva, M.H.S. Silva, H.C.N. Tolentino, L.M. Volpe, V.B. Zilli, G.S. de Albuquerque
LNLS, Campinas, Brazil
Funding:Ministry of Science, Technology and Innovation (MCTI) CARNAÚBA (Coherent X-Ray Nanoprobe Beamline) is the longest beamline at Sirius Light Source at the Brazilian Synchrotron Light Laboratory (LNLS), working in the energy range between 2.05 and 15 keV and hosting two stations: the sub-microprobe TARUMÃ, with coherent beam size varying from 550 to 120 nm; and the nanoprobe SAPOTI, with coherent beam size varying from 150 to 30 nm. Due to the long distances from the insertion device to the stations (136 and 143 m) and the extremely small beam sizes, the mechanical stability of all opto-mechanical systems along the facility is of paramount importance. In this work we present a comprehensive set of measurements of both floor stability and modal analyses for the main components, including: two side-bounce mirror systems; the four-crystal monochromator; the Kirkpatrick-Baez (KB) focalizing optics; and the station bench and the sample stage at TARUMÃ. To complement the components analyses, we also present synchronized long-distance floor acceleration measurements that make it possible to evaluate the relative stability through different floor slabs: the accelerator slab, over which the insertion device and first mirror are installed; experimental hall slab, which accommodates the second mirror; and the slabs in satellite building, consisting of three inertial blocks lying over a common roller-compacted concrete foundation, the first with the monochromator and the remaining ones with an station each. In addition to assessing the stability across this beamline, this study benchmarks the in-house design of the recently-installed mirrors, monochromators and end-stations.
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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B.K. Popovic, S.H. Lee, S. Sorsher, K.J. Suthar, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents
ANL, Lemont, Illinois, USA
A.E. Siy
UW-Madison, Madison, Wisconsin, USA
Funding:This manuscript is based upon work supported by Laboratory Directed Research and Development (LDRD) funding from Argonne National Laboratory This paper outlines the design of a diamond vacuum window and a millimeter wavelength (mmWave) waveguide assembly that will hold vacuum but still allow the mmWaves to propagate out of the structure for diagnosis and thermal management purposes. Currently under development at Argonne is a corrugated wakefield accelerator (CWA) that will operate at mmWave frequencies, with its fundamental mode of operation at 180 GHz, and relatively high power levels, up to 600 W. The fundamental mode needs to be extracted from the accelerator at approximately every 0.5 m to prevent the unwanted heating of the accelerator structure. Therefore, the structure is intentionally designed so this fundamental mode does not propagate further, instead it is transmitted through the waveguide assembly under vacuum and out via the vacuum window. As a result of the relatively high mmWave power densities, CVD diamond was chosen as the vacuum window material, due to its low electromagnetic losses, mechanical strength, and for its superior thermo-physical properties. Mechanically it is necessary to be able to hold the tight tolerances necessary for windows performance at millimeter wavelengths. Other mechanical difficulties involve assembly of the window due to CVD diamond material and preservation of ultra high vacuum even if the integrity of the CVD diamond window is somehow compromised.
