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

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 CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller 3

Previous performances on stabilization C. Montag, DESY 1996 S. Redaelli, CERN 2004 J. Frisch, SLAC 2001 B. Bolzon, LAPP 2007 CLICMeeting100409 C. Hauviller

Mock-up built in 2004 (S. Redaelli) Test set-up used by S. Raedelli

Performance at CERN Stabilisation single d.o.f. with small weight (“membrane”) 1.2 nm This is a marble, not a TMC table... CLICMeeting100409 C. Hauviller 6

CLICMeeting100409 C. Hauviller

CLICMeeting100409 C. Hauviller

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. CLICMeeting100409 C. Hauviller

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: http://clic-study.web.cern.ch/CLIC-Study/CLIC_Stabilisation/Index.htm CLICMeeting100409 C. Hauviller

Precision versus size CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller

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,…) CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller

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

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 CLICMeeting100409 C. Hauviller

Sensors Reference test bench Characterisation commercial devices by comparison Reference test bench Low technical noise lab TT1 (< 2 nm rms 1Hz) Instrument Noise determination CLICMeeting100409 C. Hauviller K. Artoos, CLIC-ACE5 03.02.2010 17

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 CLICMeeting100409 C. Hauviller

Sensors Optical STS-1 GURALP T6D PSD ENDEVCO PCB Slaathaug M. Guinchard Guralp : Noise @ 0.1 Hz (catalog) PCB: Noise @ ~10 Hz Endevco+Amplifier: Noise @ ~2 Hz CLICMeeting100409 C. Hauviller 19

Sensors Present choice: Guralp T6D seismic Geophone 0.3-0.4 nm Integrated RMS noise @ 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? CLICMeeting100409 C. Hauviller 20

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: 0.1 nm Correction with beam-based feedback Mechanical stability of main beam quadrupoles “Slow” motion “Fast” motion CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller 22

1nm Measured on the floor 5nm 2 nm Vertical Lateral CLICMeeting100409 C. Hauviller M. Sylte, M. Guinchard 23

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 CLICMeeting100409 C. Hauviller

Measurements in the LHC tunnel PSD of all the measurement points (vertical) Technical noise increases next to the experimental hall CLICMeeting100409 C. Hauviller

Characterize vibrations/environmental noise Correlation over long distances in LHC tunnel Coherence using a theoretical model (ATL law) Calculated from measurements (2008) CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller 27

Characterize vibrations/environmental noise Vertical ground motion Additional technical noise: Reference Reference Ref. : CLICMeeting100409 C. Hauviller 28 28

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) CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller 31

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 CLICMeeting100409 C. Hauviller 32

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)

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 CLICMeeting100409 C. Hauviller

Stabilization strategies CLICMeeting100409 C. Hauviller

Feedback Similar in size: the ELT project 2952 actuators 5604 sensors A. PREUMONT et al. (Presented to the Smart09 - July 2009) CLICMeeting100409 C. Hauviller

How to support the quadrupoles? Comparison control laws and former stabilisation experiments … CLICMeeting100409 C. Hauviller 37

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,…. CLICMeeting100409 C. Hauviller 38

How to support the quadrupoles? Robustness to external force (compliance) CLICMeeting100409 C. Hauviller

How to support the quadrupoles? Decision to study two options in parallel: LAPP option: soft support CERN option: rigid support CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller 41

Option LAPP: Status: Construction + tests on elastomer CLICMeeting100409 C. Hauviller 42

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 CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller 44

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 CLICMeeting100409 C. Hauviller 45

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. CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller 47

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 Feedback @ 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 CLICMeeting100409 C. Hauviller 48

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 CLICMeeting100409 C. Hauviller 49

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 CLICMeeting100409 C. Hauviller 50

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 CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller A.Jeremie, C.Hauviller September 22, 2009

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 CLICMeeting100409 C. Hauviller

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! CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 Increase damping C. Hauviller MB quad alignment with excentric cams 55

Main beam quadrupole Under manufacturing Plain material (incompatible with corrector magnet) Assembly methods to be tested (accuracy of some microns!) CLICMeeting100409 C. Hauviller

CLICMeeting100409 C. Hauviller

Upgraded in NSRRC 32 Hz for 10 tons CLICMeeting100409 C. Hauviller

What should be avoided Avoid flexible floor (damping mass?) Minimize technical noise: silent pumps, slow speed ventilation,… … CLICMeeting100409 C. Hauviller

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 CLICMeeting100409 C. Hauviller 60

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 CLICMeeting100409 C. Hauviller 61

When 1nm at 1Hz will be achieved? CLICMeeting100409 C. Hauviller