MEDSI2016 - Table of Session: TUCA (Precision Mechanics, Facility Design and Updates)

Paper	Title	Page
TUCA01	Investigation of the Vibrational Stability of Synchrotron X-Ray Optics Using a Differential Interferometer
	R. Doehrmann, J. Heuer, J. Horbach, H. Schulte Schrepping, I. Sergeev DESY, Hamburg, Germany
	Advanced synchrotron radiation experiments for example for investigations at the nanoscale place extreme demands on the stability and precision of all components of modern beamlines. This is of particular importance for high precision X-ray optics, as mirrors or double crystal monochromators (DCM), which should keep the beam stable. The DCM is the first optical element in most synchrotron beamlines, which has to operate under high heat load. Thus, the cryogenic cooling and high vacuum are necessary conditions for the DCM operation in most cases. Unfortunately, cryogenic cooling is a source of the vibrational instability that has to be reduced in order to improve the beamline performance. Here, we present a method to measure vibration directly at the DCM crystals. This method was used to study and improve vibrational stability of several PETRA III monochromators. The results of the measurements allow us to discover common sources of instabilities. These results will be shown and discussed and we will describe in detail the modifications performed on the LN2 system and the monochromator design, which leads to the improvement of the angular stability at the best down to 50 nrad RMS.
	Slides TUCA01 [9.083 MB]
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TUCA02	Structural Dynamic Modelling and Measurement of SwissFEL Bunch Compressor	128
	X. Wang, H. Jöhri, F. Löhl, M. Pedrozzi, T. Stapf PSI, Villigen PSI, Switzerland
	Magnetic chicanes are used in accelerator facilities to longitudinally compress the accelerated particle bunches. The second compression chicane (BC2) of SwissFEL consists of four dipole magnets bending the beam on the horizontal plane along a C-shaped orbit and has a total length of 17 m. The position of the two central dipoles can be continuously adjusted to achieve the required transverse offset in order to realize a wide range of compression schemes. To ensure the requires mechanical stability of the accelerator components sitting on the long and movable steel girder (7.7 m), it is essential to design a stiff support structure with high eigen frequencies. In the design stage, displacement frequency responses are calculated in a modal based linear dynamic analysis using finite element method to ensure vibration amplitude below 1 micrometer. Special considerations are given to the modelling of linear guide systems, as they introduce nonlinear support conditions and need to be adequately simplified in the calculation. After completing the BC2 assembly, vibration measurements were performed. Finally, the validation of the numerical model by measurement results will be presented.
	Slides TUCA02 [3.884 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2016-TUCA02
About •	paper received ※ 10 September 2016 paper accepted ※ 20 September 2016 issue date ※ 22 June 2017
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TUCA03	Estimation of the Temperature Fluctuations Harshness Regarding Stability of Structures in the Nanometer Range	133
	N. Jobert, F. Alves, S.K. Kubsky SOLEIL, Gif-sur-Yvette, France
	Thermally induced distortions are a key contributor to the overall positional and pointing performance of high-stability systems. Though stability scales with temperature fluctuations, there is some hidden complexity is the subject. Firstly, not all temperature oscillations will distort the structure: fast variations will hardly propagate into the structure, little change in overall dimensions but primarily pointing errors. Conversely, slow variations will result in quasi uniform temperature fields that change dimensions, hence mainly positional errors. Secondly, there is randomness in temperature fluctuations which obscures the actual severity of a given environment: randomness occurs timewise, but also space-wise. For highly stable situations, random part of the temperature field becomes prominent, and discarding this component becomes questionable. No harshness indicator exists that could help quantifying the actual severity of a given thermal environment. It is the objective of this paper to provide some insight on the matter, and propose a simple yet efficient numerical method allowing the evaluation of actual structural response to any realistic thermal environment.
	Slides TUCA03 [7.080 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2016-TUCA03
About •	paper received ※ 01 September 2016 paper accepted ※ 20 September 2016 issue date ※ 22 June 2017
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TUCA04	Vibrational Stability of a Cryocooled Horizontal-Bounce Double Crystal Monochromator
	P. Kristiansen FMB Oxford, Oxford, United Kingdom
	There is an increasing demand on monochromators to preserve the performance of the latest ultra-stable storage rings. One method of obtaining near-complete vertical preservation of the ring stability is to arrange the crystals in a horizontal diffracting geometry. We present the vibrational performance of a fixed offset Horizontal Double Crystal Monochromator. We have made direct measurements, at cryocooled conditions, on a H-DCM currently deployed at MAX IV that has a relative pitch stability of 25 nrad RMS, 1-2500 Hz, and an absolute pitch stability of 18 nrad RMS, 2-2500 Hz, when running the cryocooler in a condition that allows 1.5kW to be extracted via the circulating liquid nitrogen. These results demonstrate the advantage in terms of vibrational stability of circulating the liquid nitrogen high pressures, which enables the flow velocities to be reduced to obtain equivalent cooling performance. The value of performing live measurements is illustrated as we show that a vibration of the in-vacuum cryoline support structure is not translated into relative crystal vibrations, contrary to the intuitive assumption that this would be the primary source of beam instability.
	Slides TUCA04 [2.423 MB]
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TUCA05	The New High Dynamics DCM for Sirius	141
	R.R. Geraldes, R.M. Caliari, G.B.Z.L. Moreno, L. Sanfelici, M. Saveri Silva, N.M. Souza Neto, H.C.N. Tolentino, H. Westfahl Jr. LNLS, Campinas, Brazil T.A.M. Ruijl, R.M. Schneider MI-Partners, Eindhoven, The Netherlands
	Funding: Brazilian Ministry of Science, Technology, Innovation and Communication The monochromator is known to be one of the most critical optical elements of a synchrotron beamline, since it directly affects the beam quality with respect to energy and position. The new 4th generation machines, with emittances in the range of order of 100 pm rad, require even higher stability performances, in spite of the still conflicting factors such as high power loads, power load variation, and vibration sources. A new high-dynamics DCM (Double Crystal Monochromator) is under development at the Brazilian Synchrotron Light Laboratory for the future X-ray undulator and superbend beamlines of Sirius. Aiming at an inter-crystal stability of a few tens of nrad (even during the Bragg angle motion for flyscans) and considering the limitations of current DCM implementations, several aspects of the DCM engineering are being revisited. In order to achieve a highly repeatable dynamic system, with a servocontrol bandwidth in the range of 200 Hz to 300 Hz, solutions are proposed for a few topics, including: actuators and guides, metrology and feedback, LN2 indirect cooling, crystal clamping, thermal management and shielding. The concept of this high-dynamics DCM will be presented.
	Slides TUCA05 [2.254 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2016-TUCA05
About •	paper received ※ 11 September 2016 paper accepted ※ 20 September 2016 issue date ※ 22 June 2017
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUCA06	The Girders System for the New ESRF Storage Ring	147
	F. Cianciosi, T. Brochard, Y. Dabin, L. Goirand, M. Lesourd, P. Marion, L. Zhang ESRF, Grenoble, France
	The ESRF is proceeding with the design and procurement of its new low emittance storage ring (Extremely Brilliant Source project). This completely new storage ring requires a high performance support system, providing high stability (first resonance frequency about 50Hz) and a precise alignment capability (50µm, manual in transverse direction and motorized in the vertical one). In order to meet these requirements we decided to support the magnets of each of the 32 cells of the synchrotron with four identical girders that was considered the best compromise between cost, complexity and performances. Each of the resulting 128 girders is 5.1m long, carries about seven tons of magnets, and its weight including fixed basement and adjusting system is six tons. The adjustment system relies on modified commercial wedges; their stiffness was evaluated through laboratory tests. The FEA calculations carried out to optimize the design will be presented, together with the results obtained on a complete prototype girder system which was built and extensively tested and confirmed the modal calculations.
	Slides TUCA06 [17.229 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2016-TUCA06
About •	paper received ※ 07 September 2016 paper accepted ※ 19 September 2016 issue date ※ 22 June 2017
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUCA07	An Overview of the European Spallation Source
	X. Permanyer ESS, Lund, Sweden
	ESS, the European Spallation Source, will be a major user facility at which researchers from academia and industry will investigate scientific questions using neutron beams. ESS will be a slow neutron source of unparalleled power and scientific performance. The ESS is divided in three main areas: accelerator, target and experiments. The accelerator creates protons at the ion source, accelerates them to an appropriate energy and steers them to a solid, rotating tungsten target. The target converts the high energy proton beam into low-energy neutron beams via the spallation process with the greatest possible efficiency. The neutrons will be delivered to a suite of research instruments, each devised to extract different kinds of information from the samples studied. ESS will reach its full design specifications in 2025, with a suite of 22 research instruments.
	Slides TUCA07 [48.115 MB]
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

TUCA01

Investigation of the Vibrational Stability of Synchrotron X-Ray Optics Using a Differential Interferometer

R. Doehrmann, J. Heuer, J. Horbach, H. Schulte Schrepping, I. Sergeev
DESY, Hamburg, Germany

Advanced synchrotron radiation experiments for example for investigations at the nanoscale place extreme demands on the stability and precision of all components of modern beamlines. This is of particular importance for high precision X-ray optics, as mirrors or double crystal monochromators (DCM), which should keep the beam stable. The DCM is the first optical element in most synchrotron beamlines, which has to operate under high heat load. Thus, the cryogenic cooling and high vacuum are necessary conditions for the DCM operation in most cases. Unfortunately, cryogenic cooling is a source of the vibrational instability that has to be reduced in order to improve the beamline performance. Here, we present a method to measure vibration directly at the DCM crystals. This method was used to study and improve vibrational stability of several PETRA III monochromators. The results of the measurements allow us to discover common sources of instabilities. These results will be shown and discussed and we will describe in detail the modifications performed on the LN2 system and the monochromator design, which leads to the improvement of the angular stability at the best down to 50 nrad RMS.

Slides TUCA01 [9.083 MB]

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUCA02

Structural Dynamic Modelling and Measurement of SwissFEL Bunch Compressor

128

X. Wang, H. Jöhri, F. Löhl, M. Pedrozzi, T. Stapf
PSI, Villigen PSI, Switzerland

Magnetic chicanes are used in accelerator facilities to longitudinally compress the accelerated particle bunches. The second compression chicane (BC2) of SwissFEL consists of four dipole magnets bending the beam on the horizontal plane along a C-shaped orbit and has a total length of 17 m. The position of the two central dipoles can be continuously adjusted to achieve the required transverse offset in order to realize a wide range of compression schemes. To ensure the requires mechanical stability of the accelerator components sitting on the long and movable steel girder (7.7 m), it is essential to design a stiff support structure with high eigen frequencies. In the design stage, displacement frequency responses are calculated in a modal based linear dynamic analysis using finite element method to ensure vibration amplitude below 1 micrometer. Special considerations are given to the modelling of linear guide systems, as they introduce nonlinear support conditions and need to be adequately simplified in the calculation. After completing the BC2 assembly, vibration measurements were performed. Finally, the validation of the numerical model by measurement results will be presented.

Slides TUCA02 [3.884 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2016-TUCA02

About •

paper received ※ 10 September 2016 paper accepted ※ 20 September 2016 issue date ※ 22 June 2017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUCA03

Estimation of the Temperature Fluctuations Harshness Regarding Stability of Structures in the Nanometer Range

133

N. Jobert, F. Alves, S.K. Kubsky
SOLEIL, Gif-sur-Yvette, France

Thermally induced distortions are a key contributor to the overall positional and pointing performance of high-stability systems. Though stability scales with temperature fluctuations, there is some hidden complexity is the subject. Firstly, not all temperature oscillations will distort the structure: fast variations will hardly propagate into the structure, little change in overall dimensions but primarily pointing errors. Conversely, slow variations will result in quasi uniform temperature fields that change dimensions, hence mainly positional errors. Secondly, there is randomness in temperature fluctuations which obscures the actual severity of a given environment: randomness occurs timewise, but also space-wise. For highly stable situations, random part of the temperature field becomes prominent, and discarding this component becomes questionable. No harshness indicator exists that could help quantifying the actual severity of a given thermal environment. It is the objective of this paper to provide some insight on the matter, and propose a simple yet efficient numerical method allowing the evaluation of actual structural response to any realistic thermal environment.

Slides TUCA03 [7.080 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2016-TUCA03

About •

paper received ※ 01 September 2016 paper accepted ※ 20 September 2016 issue date ※ 22 June 2017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUCA04

Vibrational Stability of a Cryocooled Horizontal-Bounce Double Crystal Monochromator

P. Kristiansen
FMB Oxford, Oxford, United Kingdom

There is an increasing demand on monochromators to preserve the performance of the latest ultra-stable storage rings. One method of obtaining near-complete vertical preservation of the ring stability is to arrange the crystals in a horizontal diffracting geometry. We present the vibrational performance of a fixed offset Horizontal Double Crystal Monochromator. We have made direct measurements, at cryocooled conditions, on a H-DCM currently deployed at MAX IV that has a relative pitch stability of 25 nrad RMS, 1-2500 Hz, and an absolute pitch stability of 18 nrad RMS, 2-2500 Hz, when running the cryocooler in a condition that allows 1.5kW to be extracted via the circulating liquid nitrogen. These results demonstrate the advantage in terms of vibrational stability of circulating the liquid nitrogen high pressures, which enables the flow velocities to be reduced to obtain equivalent cooling performance. The value of performing live measurements is illustrated as we show that a vibration of the in-vacuum cryoline support structure is not translated into relative crystal vibrations, contrary to the intuitive assumption that this would be the primary source of beam instability.

Slides TUCA04 [2.423 MB]

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUCA05

The New High Dynamics DCM for Sirius

141

R.R. Geraldes, R.M. Caliari, G.B.Z.L. Moreno, L. Sanfelici, M. Saveri Silva, N.M. Souza Neto, H.C.N. Tolentino, H. Westfahl Jr.
LNLS, Campinas, Brazil
T.A.M. Ruijl, R.M. Schneider
MI-Partners, Eindhoven, The Netherlands

Funding: Brazilian Ministry of Science, Technology, Innovation and Communication
The monochromator is known to be one of the most critical optical elements of a synchrotron beamline, since it directly affects the beam quality with respect to energy and position. The new 4th generation machines, with emittances in the range of order of 100 pm rad, require even higher stability performances, in spite of the still conflicting factors such as high power loads, power load variation, and vibration sources. A new high-dynamics DCM (Double Crystal Monochromator) is under development at the Brazilian Synchrotron Light Laboratory for the future X-ray undulator and superbend beamlines of Sirius. Aiming at an inter-crystal stability of a few tens of nrad (even during the Bragg angle motion for flyscans) and considering the limitations of current DCM implementations, several aspects of the DCM engineering are being revisited. In order to achieve a highly repeatable dynamic system, with a servocontrol bandwidth in the range of 200 Hz to 300 Hz, solutions are proposed for a few topics, including: actuators and guides, metrology and feedback, LN2 indirect cooling, crystal clamping, thermal management and shielding. The concept of this high-dynamics DCM will be presented.

Slides TUCA05 [2.254 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2016-TUCA05

About •

paper received ※ 11 September 2016 paper accepted ※ 20 September 2016 issue date ※ 22 June 2017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUCA06

The Girders System for the New ESRF Storage Ring

147

F. Cianciosi, T. Brochard, Y. Dabin, L. Goirand, M. Lesourd, P. Marion, L. Zhang
ESRF, Grenoble, France

The ESRF is proceeding with the design and procurement of its new low emittance storage ring (Extremely Brilliant Source project). This completely new storage ring requires a high performance support system, providing high stability (first resonance frequency about 50Hz) and a precise alignment capability (50µm, manual in transverse direction and motorized in the vertical one). In order to meet these requirements we decided to support the magnets of each of the 32 cells of the synchrotron with four identical girders that was considered the best compromise between cost, complexity and performances. Each of the resulting 128 girders is 5.1m long, carries about seven tons of magnets, and its weight including fixed basement and adjusting system is six tons. The adjustment system relies on modified commercial wedges; their stiffness was evaluated through laboratory tests. The FEA calculations carried out to optimize the design will be presented, together with the results obtained on a complete prototype girder system which was built and extensively tested and confirmed the modal calculations.

Slides TUCA06 [17.229 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2016-TUCA06

About •

paper received ※ 07 September 2016 paper accepted ※ 19 September 2016 issue date ※ 22 June 2017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUCA07

An Overview of the European Spallation Source

X. Permanyer
ESS, Lund, Sweden

ESS, the European Spallation Source, will be a major user facility at which researchers from academia and industry will investigate scientific questions using neutron beams. ESS will be a slow neutron source of unparalleled power and scientific performance. The ESS is divided in three main areas: accelerator, target and experiments. The accelerator creates protons at the ion source, accelerates them to an appropriate energy and steers them to a solid, rotating tungsten target. The target converts the high energy proton beam into low-energy neutron beams via the spallation process with the greatest possible efficiency. The neutrons will be delivered to a suite of research instruments, each devised to extract different kinds of information from the samples studied. ESS will reach its full design specifications in 2025, with a suite of 22 research instruments.

Slides TUCA07 [48.115 MB]

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)