1. Stabilization of the quadrupoles of the main linac One of the CLIC feasibility issues C. Hauviller/ EN
CLIC Meeting April 9, 2010

2. CLIC stabilization requirements
Mechanical stabilization requirements: Quadrupole magnetic axis vibration tolerances:
Main beam quadrupoles to be mechanically stabilized:
A total of about 4000 main beam quadrupoles
4 types: Type 1 (~ 100 kg), 2, 3 and 4 (~400 kg)
Magnetic length from 350 mm to 1850 mm
Mechanical stabilization might be On at some quads and Off of some others
Final Focus quadrupoles
Main beam quadrupoles
Vertical
0.1 nm > 4 Hz
1 nm > 1 Hz
Horizontal
5 nm > 4 Hz
5 nm > 1 Hz
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3. How to measure the performances?
Compute the integrated r.m.s. displacement at n Herz from the measured PSD (Power Spectral Density)
Random vibrations (exact term) >> P.S.D. Observation: the level goes down with frequency
The summing from infinite frequency down to 1 Hz. Practically we see that from some upper limit the participation can be neglected
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4. Previous performances on stabilization
C. Montag, DESY 1996
S. Redaelli, CERN 2004
J. Frisch, SLAC 2001
B. Bolzon, LAPP 2007
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5. Mock-up built in 2004 (S. Redaelli)
Test set-up used by S. Raedelli

6. Performance at CERN
Stabilisation single d.o.f. with small weight (“membrane”)
1.2 nm
This is a marble, not a TMC table...
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9. Remarks Active vibration control is not yet a mature technology.
Activity should be defined as R&D but with CLIC engineering as objective.
It will take time to achieve the final objective but a work plan has been agreed in March 2008 with CDR as an important milestone
Most of the collaborators have background on vibrations but not on the specific field of stabilization.
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10. Approach Competency center: understand the subject in depth
Build a knowledgeable team
Use the existing know-how spread in many places:
Previous theses ( in particular Montag, Redaelli, Bolzon,…)
Work done in the labs: Low emittance Light sources, FEL, ILC,…
Work (mainly) in the universities on lithography, satellites and radiotelescopes
Apply to realistic mock-up(s)
Create a reference web site:
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11. Precision versus size
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12. Contents R & D Actions Integrate and apply to CLIC The team Sensors
Characterize vibrations/environmental noise
Actuators
Feedback
Test mock-ups
Integrate and apply to CLIC
CDR and TDR
The team
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13. Sensors Program of work
State of the art of sensor development and performances (updated on a yearly basis)
Calibrate by comparison.
Interferometer to calibrate other sensors
Create a reference test set-up (at CERN)
Qualification with respect to accelerator environment (EMC, radiation,…)
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14. State of the art of ground motion sensors
Table of Contents
Characteristics
Sensor noise
Noise sources
Noise detection
Sensitivity
Resolution
Sensor types
Geophone
Accelerometer
Feedback seismometer
Capacitive distancemeter
Stretched wire system
Other sensor
Comparison
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15. Sensors How to measure nanometers and picometers ? Catalogue products
Absolute velocity/acceleration measurements
Seismometers (geophones)
Accelerometers (seismic - piezo)
Streckeisen
STS2
Guralp
CMG 3T
CMG 40T
2*750Vs/m
2*800Vs/m
30 s -50 Hz
120 s -50 Hz
360s -50 Hz
x,y,z
13 kg
13.5 kg
7.5 kg
Eentec
SP500
PCB
393B31
2000Vs/m
60 s -70 Hz
1.02Vs2/m z
10 s -300 Hz
0.750 kg
0.635 kg
electrochemical
CMG 6T
2*1000Vs/m
30s-80Hz
Improved performances
Lab environment

16. Sensors Relative displacement/velocity
Capacitive gauges : Best resolution 10 pm (PI) , 0 Hz to several kHz
Linear encoders : Best resolution 1 nm (Heidenhain)
Vibrometers (Polytec) ~1nm at 15 Hz
Interferometers
Industrial products (SIOS, Renishaw, Attocube) <1 nm at 1 Hz
(CEA-IRFU)
Low cost “Optical transducer” under development <1nm at 1Hz Compact Straightness Monitor MONALISA at Oxford
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17. Sensors Reference test bench
Characterisation commercial devices by comparison
Reference test bench
Low technical noise lab TT1 (< 2 nm rms 1Hz)
Instrument Noise determination
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K. Artoos, CLIC-ACE 17

18. Sensors Characterization for low intensity signals: Which sensor?
Quality of its measurement?
Sensitivity + resolution
Cross axis sensitivity
Noise level, « self noise » measurement (ex. blocking the seismic mass or by coherence)
Measuring procedure (influence of the environment)
Signal processing: Resolution, filtering, window, FFT, DSP,
integration, coherence
Noise determination by comparison
2 geophones and 2 accelerometers
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19. Sensors Optical STS-1 GURALP T6D PSD ENDEVCO PCB Slaathaug
M. Guinchard
Guralp : 0.1 Hz (catalog)
PCB: ~10 Hz
Endevco+Amplifier: ~2 Hz
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20. Sensors Present choice: Guralp T6D seismic Geophone
nm Integrated RMS 1 Hz
But
sensitive to magnetic field
sensitive to radiation
large dimensions (~ proportional to sensitivity)
Eentec SP500 electro chemical seismometer
radiation and magnetic field hard
found unstable with time
In the future:
Adapt existing device or develop new ones?
e.g. Michelson interferometer SIOS used for pole tips measurements could be used as reference sensor?
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21. Acoustic noise becomes very important
Characterize vibrations/environmental noise Environmental vibration levels – orders of magnitude, CERN site
LEP ground motion during 1 year
300 µm – 1 mm
Geophones
Alignment
Accelerometers
Ground motion due to Lunar cycle (tides)
Several µm
Cultural noise
Acoustic noise becomes very important
7 sec hum
100 nm, CLEX
10 nm, CLEX
Required vertical stability for all main linac quads for CLIC: 1 nm
Required vertical stability for Final Focus quads for CLIC: nm
Correction with beam-based feedback
Mechanical stability of
main beam quadrupoles
“Slow” motion
“Fast” motion
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22. Characterize vibrations/environmental noise
What level of vibrations can be expected on the ground?
Several measurement campaigns: LAPP, DESY, CERN....
LHC
Effort continued by CERN in 2009
PSI
CesrTA
AEGIS
CLEX
CMS
Metrology Lab
2009
Lab
TT1
M. Sylte, M. Guinchard
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23. 1nm Measured on the floor 5nm 2 nm Vertical Lateral
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24. Measurements in the LHC tunnel
LHC DCUM 1000
~ 80 m under ground
LHC systems in operation, night time
Floor building 180
Building 180
Surface
No technical systems in operation,
night time
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25. Measurements in the LHC tunnel
PSD of all the measurement points (vertical)
Technical noise increases next to the experimental hall
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26. Characterize vibrations/environmental noise
Correlation over long distances in LHC tunnel
Coherence using a theoretical model
(ATL law)
Calculated from measurements
(2008)
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27. Characterize vibrations/environmental noise
Measurements in the LHC tunnel
Ground motion modelling
+ technical noise modelling
Former work A. Seryi, B. Bolzon
Update of 2D power spectral density for LHC tunnel in the vertical and lateral direction
Vertical and lateral models of the technical noise
Ref. C. Collette
“Description of ground motion”
ILC-CLIC LET Beam Dynamics WS 2009
Reference curves, technical noise
Models available integrated in models for stabilisation and BBF
Need to characterize precisely the vibration sources
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28. Characterize vibrations/environmental noise
Vertical ground motion
Additional technical noise:
Reference
Reference
Ref. :
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29. Actuators Program of work
State of art of actuators development and performances (updated on a yearly basis)
Develop and test various damping techniques (passive and active)
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30. State of art of actuators
Table of Contents
Introduction and requirements
Comparison of actuator principles
Different actuators
Piezo electric actuators
Electro-magnetic actuators
Magneto striction
Electro-static plates
Shape memory alloys
Scaling laws
Design of actuators for sub nanometer positioning
Hysteresis free guidance
Non contact direct metrology
X-Y kinematics
Trajectory control and dynamic accuracy + resolution considerations
Limitations
Different configurations of piezo based actuators
Providers of nano actuators and vibration isolation
Nano positioning applications
Bench mark projects
References
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31. Actuators
First selection parameter: Sub nanometre resolution and precision
Actuator mechanisms with moving parts and friction excluded (not better than 0.1 μm, hysteresis)
Solid state mechanics
+ Well established
- Fragile (no tensile or shear forces), depolarisation
Piezo electric materials
High rigidity
Rare product, magnetic field, stiffness < piezo,
force density < piezo+ No depolarisation, symmetric push-pull
Magneto Strictive materials
Risk of break through, best results with μm gaps, small force density, complicated for multi d.o.f. not commercial
Electrostatic plates
No rigidity, ideal for soft supports
Electro magnetic
(voice coils)
Heat generation, influence from stray magnetic fields for nm resolution
Shape Memory alloys
Slow, very non linear and high hysteresis, low rigidity, only traction
Electro active polymers
Slow, not commercial
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32. Resonance frequency and rigidity
Selection of piezo actuators
Resolution
0.1 nm
Positioning and/or stabilisation
Range
30 μm
Resonance frequency and rigidity
As high as possible
Prestress
Force/load capacity
Up to 100Kg
(< 20 % mechanical limit)
20 MPa for dynamic behaviour
Weight compensating spring, reduces range
Assembly
Dimensions
HVPZT or LVPZT
Required power,
frequency range controller
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33. Actuators
An example of the integration of piezo actuators PZT in an actual support
- Use of flexural guides against shear forces
- Use of a feedback capacitive sensor
0.1 nm 100 N Calibration bench flexural guides
Techniques to be applied for heavier (up to 400Kg)
and larger structures (up to 2 meter long)

34. Feedback Program of work
Develop methodology to tackle with multi degrees of freedom (large frequency range, multi-elements)
LAViSTa demonstrated feasibility on models
Similar problems elsewhere like the adaptative optics of the European ELT
Apply software to various combinations of sensors/actuators and improve resolution (noise level)
High quality acquisition systems at LAViSTa and CERN
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35. Stabilization strategies
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36. Feedback Similar in size: the ELT project
2952 actuators
5604 sensors
A. PREUMONT et al.
(Presented to the Smart09 - July 2009)
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37. How to support the quadrupoles?
Comparison control laws and former stabilisation experiments …
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38. How to support the quadrupoles? Soft versus rigid ?
Soft: + Isolation in large bandwidth
Rigid: - High resolution required actuators
But available in piezo catalogues
- But more sensitive to external forces
+ Robust against external forces
- Elastomers and radiation
+ Nano positioning
External forces: vacuum, power leads, cabling,
water cooling, interconnects, acoustic pressure,….
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39. How to support the quadrupoles?
Robustness to external force (compliance)
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40. How to support the quadrupoles?
Decision to study two options in parallel:
LAPP option: soft support
CERN option: rigid support
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41. Soft support and active vibration control
Option LAPP:
Soft support and active vibration control
Actuators positions
3 d.o.f.
Elastomeric joint
Poles are bolted on supports
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42. Option LAPP: Status: Construction + tests on elastomer
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43. Test Mock-ups (CERN) Rigid support and active vibration control
(up to 6 dof)
Stabilisation single d.o.f. with small weight (membrane)
Program going on with further improvements
2. Tripod with weight type 1 MBQ with 1 active leg
Presently under tests
3. Tripod type 1 MBQ with 3 active legs Inclined leg with flexural joints
Two inclined legs with flexural joints
Add spring guidance
Test equivalent load per leg
4. MOCK-UP Type 4 MBQ on hexapod
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44. Test Mock-ups (CERN)
1. Stabilisation single d.o.f. with small weight (“membrane”)
Theory vs measurement:
Transfer function
Measurement better< 2 Hz
Phase
Diff. > 40 Hz
Model is good representation 2-40 Hz
Differences between theory and Measurements are under investigation
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45. Test Mock-ups (CERN) For FREE
1. Stabilisation single d.o.f. with small weight (“membrane”)
Bonus: possibility to nano position the Quadrupole
Ref. D. Schulte CLIC-ACE4 : “Fine quadrupole motion”
“Modify position quadrupole in between pulses (~ 5 ms) “
“Range 20 μm, precision 2nm »
Demonstration nano positioning :
S. Janssens
open loop
Measured with PI capacitive gauge
10 nm, 50 Hz
For FREE
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46. Signal acquisition: the present limits To be overcome!
The amplitude of the ground vibrations reduces with frequency. Above some frequency, the participation to the rms integrated value becomes negligible.
The measurement in the quieter zone (TT1) was carried out with an analyzer with a resolution of 24 bit on ± 10 mV.
The amplitude of 10 pm at 20 Hz for instance corresponds to voltage amplitude of 2.5 microvolt. To recognize a sine wave we should need at least some points over its amplitude, so we need to be able to measure about 0.1 microvolt on a signal amplitude of about 10 mV.
The signal to noise ratio becomes near to 1 above 10 Hz. Any amplification or ADC should have very low noise.
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47. Test Mock-ups (CERN)
2. Stabilisation single d.o.f. with type 1 weight (“tripod”)
2 passive feet
actuator
Tripod
50 kg mass (proportional type 1)
Piezo actuator
2 passive feet
Feedforward Geophone
Feedback Geophone
Controller in Labview
Optimise controller design (Tuning, Combine feedback with feedforward)
Improve resolution (actuator, DAQ)
Avoid low frequency resonances in structure and contacts
Noise budget on each step, ADC and DAC noise
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48. Test Mock-ups (CERN)
2. Stabilisation single d.o.f. with type 1 weight(“tripod”)
2 passive feet
actuator
S. Janssens
Preliminary result
First results
10Hz tf ~0.5
Simulation done with transfer function for tt1
-> Close to 1nm up to ~ 1.5 Hz
Computer model is being built
Expected
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49. Test Mock-ups (CERN)
3. Stabilisation two d.o.f. with type 1 quadrupole weight (“tripod”)
3a. Inclined leg with flexural joints
Status: Launch first prototype flexural hinges
3b. Two inclined legs with flexural joints y x
3c. Add a spring guidance
Load compensation
(Status: start design)
Precision guidance
Reduce degrees of freedom
Reduce stress on piezo
3d. Test equivalent load/leg
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50. Test Mock-ups (CERN)
4. Stabilisation of type 4 (and type 1)CLIC MB quadrupole proto type
Lessons learnt step 1 to 3
Results Tests 1 to 3
Cost analysis
(number of legs= cost driver)
Design for the 4 types
# degrees of freedom
Stress and dynamic analysis
Range nano-positioning
Resolution
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51. Apply to CLIC Program of work (as defined in March 2008)
Linac (a demonstrator mock-up will be built)
Compatibility of linac supporting system with stabilization (including mechanical design): eigenfrequencies, coupling between girders, coupling of mechanical feedback with beam dynamics feedback,…
Design of quadrupole (we have to stabilize the magnetic axis) mock-up will have “real” physical dimensions and all mechanical characteristics but not the field quality required by CLIC
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52. MB quadrupole Mock-up Module type 4
Overall integration + Liaison with MWG: Artoos
Magnet: Modena
Modal calculations and poles: Deleglise
Stabilisation: see Options
Pre-alignment with cams: Lackner
Damped floor
To be studied
Independent measurements:
Urner, Fontaine
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A.Jeremie, C.Hauviller September 22, 2009

53. Main Beam Mock-up Functionalities Parts / Measuring devices
Demonstrate stabilization in operation:
Magnet powered, Cooling operating
Configurations
1- Stand-alone
2- Integrated in Module
3- Interconnected
Accelerator environment
Parts / Measuring devices
Floor (damping material)
Support
Pre-alignment
Stabilization
Magnet
Vacuum chamber and BPM
Independent measurement
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54. Main Beam Mock-up Compatibility between functionalities?
Stabilization is better achieved with a rigid support
Adjustable re-alignment needs a flexible support
To minimize the incompatibility, fix on a rigid ground, minimize the beam height, design “rigid” movers, “rigid” girder, magnet with “high” first eigenfrequency: a challenge!
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55. Dynamic analysis Lessons learnt from light sources:
Vibrations on the ground
Result on magnet
Transmissibilty
Broadband excitation with decreasing amplitude with increasing frequency.
Amplification at resonances
Lessons learnt from light sources:
Alignment system as rigid as possible
Increase natural frequencies ALL components
+ optionally locking of alignment
Maximise rigidity
Minimise weight (opposed to thermal stability)
Minimise beam height
(frequency and Abbé error)
Optimise support positions
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Increase damping
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MB quad alignment with excentric cams 55

56. Main beam quadrupole Under manufacturing
Plain material (incompatible with corrector magnet)
Assembly methods to be tested (accuracy of some microns!)
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57. CLICMeeting100409
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58. Upgraded in NSRRC
32 Hz for 10 tons
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59. What should be avoided Avoid flexible floor (damping mass?)
Minimize technical noise: silent pumps, slow speed ventilation,… …
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60. Organisation CLIC Stabilisation Working Group (started 2008) Mandate:
(Chairman: C.Hauviller)
Collaboration and exchanged information with:
IRFU/SIS
MONALISA
Meetings every 3 months (Stabilization days)
Mandate:
Demonstrate 1 nm quadrupoles stability above 1 Hz (Linac), in an accelerator environment, with realistic equipment, verify with independent method
Demonstrate or provide evidence of 0.1 nm stability above 4 Hz (Final Focus)
Characterize vibrations/noise sources in an accelerator
Compatibility with pre-alignment
STABWG
MDI
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61. CERN- EN LAPP LaViSta CEA-IRFU-SIS OXFORD-MONALISA Claude Hauviller
Kurt Artoos
Christophe Collette (fellow)
Stef Janssens (PhD student) supervisor Prof. A. Preumont
Pablo Fernandez (fellow)
Michael Guinchard (Mechanical measurements lab)
Andrey Kuzmin
Ansten Slaathaug (Technical student) follows up Magnus Sylte
Raphael Leuxe
LAPP LaViSta
LAPP: A. Jeremie, L. Brunetti, G. Deleglise, L. Pacquet, G. Balik
SYMME: J. Lottin, R. LeBreton (Phd student) A. Badel, B. Caron
CEA-IRFU-SIS
F. Ardellier-Desages, M. Fontaine, N. Pedrol Margaley
IRFU/SIS
OXFORD-MONALISA
D. Urner, P. Coe, A. Reichold, M. Warden
MONALISA
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62. When 1nm at 1Hz will be achieved?
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