NANO-POSITIONING POSSIBILITIES FOR FUTURE ACCELERATOR MAGNETS K. Artoos, 28 November 2014 K. Artoos, C. Collette, M. Esposito, P. Fernandez Carmona, M. Guinchard, S. Janssens, D. Tshilumba The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD

2 Outline Motivation high precision actuation of quadrupole magnets Mechanical stabilisation “nano positioning” Actuating support Actuators Actuator architecture Results Sensors for nano positioning Status for CLIC MBQ Conclusions and future research

3 K.Artoos, Stabilisation WG, 21th February 2013 Machine precision vs size C. Collette

Compact Linear Collider (CLIC) 4  Novel 2 beam concept  100 MV/m  1 chance for collisions  Vert. Beam size 1nm at ip  Hor. Beam size 40 nm at ip

5 Alignment of accelerator components Perturbations and imperfections J. Pfingstner

6 Pre-Alignment of the components Static imperfections Magnetic center, fiducialisation PACMAN Pre alignment 17 µm over 200 m

7 Pre Alignment of the components Excentric cams: Range ± 3mm, resolution 0.5 µm Wire Position Sensor : Precision 1 µm, measurement time 10 s J. Kemppinen

Ground motion 8 ~40 nm 1 nm 20 km

Other perturbations 9 Directly Applied forces water cooling, vacuum, power leads, cabling, interconnects, ventilation, acoustic pressure Temperature changes + gradients Dimension changes, deformation (creep, humidity, …)

Dynamic perturbations Stabilisation Requirements Stability (magnetic axis): Nano-positioning 3992 CLIC Main Beam Quadrupoles: 10 Type 4: 2m, 400 kgType 1: 0.5 m, 100 kg A. Samoshkin Main beam quadrupoles Final Focus Vertical 1.5 nm > 1 Hz Vertical 0.2 nm > 4 Hz Lateral 5 nm > 1 Hz Lateral 5 nm > 4 Hz  Ground motion  External forces  Flexibility of magnet

Motivation investment: Luminosity (= energy consumption) 11 No stabilization68% luminosity loss Seismometer FB maximum gain13% Seismometer FB medium gain 6% (reduced 0.1 and 75 Hz) Seismometer FB maximum gain +FF7% Inertial reference mass11% Inertial reference. mass. + HP filter3% Courtesy J. Snuverink et al. CLIC With representative ground motion model

12 Motivation nano positioning quads Beam based alignment of the components Use the beam it self as reference, measured with the BPM One-to-one correction: Measure the position of the beam steer or move magnet so that the beam goes through the center of the next BPM Dispersion free steering: change energy beam between pulses Errors of the BPM center relative to magnetic field center become visible Resolution BPM 100 to 50 nm Courtesy D.Schulte, J. Pfingstner

Nano positioning 13 « Nano-positioning» feasibility study Modify position quadrupole in between pulses (~ 5 ms) Range ± 5 μ m, increments 10 to 50 nm, precision ± 0.25 nm Lateral and vertical In addition/ alternative dipole correctors ( bending radius) Use to increase time to next realignment with cams

Boundary conditions actuating system 14 Accelerator environment High radiation Stray magnetic field Large temperature variations Stiffness-Robustness Applied forces (water cooling, vacuum, power leads, cabling, interconnects, ventilation, acoustic pressure) Nano positioning Transportability/Installation Available space Mass of the magnet Inputs (ground motion sensors): example CLIC Resolution 2 µV Dynamic range 60 dB Bandwidth Hz Output: Dynamic range 140 dB

Actuators for precision mechatronics 15 Piezo electric actuators Bulk actuators Stack (+ Bimorph) Periodic actuators

Design constraints Piezo (in a nut shell) 16 Depolarisation above Curie temperature (< 80C/150C bake out!) Ceramic material (small traction stress, bending or shear stress) Need of preload springs + guidance (elastic ) Mass ≠ force Stress < depolarisation stress A Range Force

Dynamic constraints piezo 17 Mechanical constraint: Electrical constraints: (Break down voltage piezo) steady state position piezo = ~ 0 W Electrical power amplifier (slew rate) For high frequency: heating of piezo Frequency Amplitude Load compensation reduces range + bandwidth Improves resolution *

Actuators for precision mechatronics 18 Electro magnetic actuators: F= kf.I Zero stiffness No lateral forces Non linear Magneto strictive actuators e.g. Terfenol D “voice coil” Stepper motor linked to a screw/nut Limited in resolution by friction (1-(0.1) µm) Harmonic drive r: ,  ~ 80% Satellite Roller screws ~ % Slow, power consumption Rare Robust, similar stiffness as piezo High loads Slightly higher range compared to piezo ( ppm) No permanent depolarisation after T >T Curie Push pull actuators are possible Power dissipation in coil

Actuators for precision mechatronics 19 [ from Pons, Emerging actuator technologies]

Actuators for precision mechatronics 20 [ from Pons, Emerging actuator technologies]

Strategy Support CLIC MBQ Stiff structure At least four d.o.f. Precise motion Repeatability 0.1 nm resolution vertically Parallel structure Stiff piezo actuators Flexural hinges 21

K. Artoos, ACE 6, Geneva 2nd February 2011 Structural stiffness Induced stresses in piezo Inclination Resolution, structure stiffness, forces Number # D.O.F., COST Resonant frequency Solution 4 types Strategy Support Block longitudinal Block roll X-Y flexural guide 22

Actuator architecture 23 Researched Configurations Final 2D design + Stiff + Cost effective - Only 2 d.o.f. control

Concept for MBQ Actuating support 24 Inclined stiff piezo actuator pairs with flexural hinges (vertical + lateral motion) (four linked bars system) X-y flexural guide to block roll + longitudinal d.o.f.+ increased lateral stiffness. Flexural pins

25 Type 1 Collocated pair X-y proto Seismometer FB max. gain +FF (FBFFV1mod): 7 % luminosity loss (no stabilisation 68 % loss) Concept demonstration Active vibration stabilisation EUCARD deliverable

Sensors for precision mechatronics 26 Capacitive sensor 3 beam interferometer Optical incremental encoder Actuators equipped with strain gauges

X-y positioning: Study precision, accuracy and resolution 27

Nano positioning 28 1&2 Flexural guide increases lateral stiffness by factor 500, band width without resonances to ~100 Hz

Comparison sensors 29 SensorResolutionMain +Main - Actuator sensor0.15 nmNo separate assemblyResolution No direct measurement of magnet movement Capacitive gauge0.10 nmGauge radiation hardMounting tolerances Gain change w.  Orthogonal coupling Interferometer10 pmAccuracy at freq.> 10 HzCost Mounting tolerance Sensitive to air flow Orthogonal coupling Optical ruler0.5*-1 nmCost 1% orthogonal coupling Mounting tolerance Small temperature drift Possible absolute sensor Rad hardness sensor head not known Limited velocity displacements Seismometer (after integration)< pm at higher frequenciesFor cross calibration K.Artoos, Stabilisation WG, 21th February 2013

Assembly type 1 MBQ 30 A stiff but light Fixed frame around the mobile part, objective Natural frequencies > 100 Hz

Concept for MBQ 31 Central fixed part Magnet mounted with assembly tool

Concept for MBQ 32

Concept for MBQ 33

Concept for MBQ 34

Displacement sensors 35 + actuator gauges, interferometer + seismometers (calibration)

36

37 First measurements vibrations, especially laterally= presence mode Good precision Calibration is needed for a better accuracy Horizontal motion: (with gain correction for roll)

Type 1 modes 38 z y x October 2014 Modal analysis of structure Mode shapes of plate Both modes deform the bottom plate Motion around x and z axis Asymetric due to asymetric supports No rotation of the magnet (from raw data) Lack of stiffness of the plate in the centre due to holes in the bottom plate (?) x z x z D. Zsiemianski

39 Testing of the range

40 Conclusions Future research Stabilisation and nano positioning was technically demonstrated Models predict for CLIC that stabilisation can improve luminosity by > 50 % with a rather “small” investment (< 5% of machine cost versus saved energy consumption) “Nano positioning” of magnets improves further luminosity + might replace corrector dipoles. Before technical implementation several things to be researched/validated: e.g. radiation, temperature changes,…. A Limiting factor : mass of the magnet linked to range of stiff actuating system Research on long range actuating system ? How to reduce the mass to be moved

41 Spare slides

ModeFreq. (Hz) Shape 1115Longitudinal Lateral Rotation Z 4241Lateral mode frame 5299Vertical Roll Magnet Type 1 Modal analysis B.C. : Earth gravity on, fixed support 4 outer faces support plate. All parts present + bonded

Type 1 modes 43 z y x Removed stepwise frame: No significant changes each step Slight change in first mode (weight reduction) June 2014 z x Bottom plate or frame different in model? S. Janssens

Type 1 modes 44 July 2014 Simulations performed suggesting reduced stiffness in profiles screwed vs glued. => Glued bottom profiles What is the difference bolted vs glued connection? Six cases reviewed (three important): Configuration 4: the bottom face of the profile is fixed Configuration 5: the bottom face of the Base is fixed (connection with profile bolts) Configuration 6: the bottom face of the Base is fixed and the profile is bonded to the plate and the base.

ModeFreq. (Hz) Ref Sl 4 Shape 14458Longitudinal Lateral Vertical Rotation Z Pitch Magnet Roll Magnet Type 1 Modal analysis B.C. : Earth gravity on, fixed support 4 CORNERS support plate. Is an exaggeration, removes rigidification by B.C. Frame + Longitudinal profile removed. Contact lateral stiffeners to fixed plate replaced by 1 edge contact Vertical and rotation modes inverse, But we know there is no vertical mode below 200 Hz 50 μm bending

Positioning 46 Requested position-actual position = error Position control -Proportional Integral (PI) Controller -g increases step speed -Integrator removes offset -(additional Derivative control (PID) adds damping) R

47 Compatibility of cascaded systems BPMBPM (m) Alignment Magn. Fidu. BPM Nanopos. Stabilisation Range Accuracy Precision/resolution  Each system position should be unique within each resolution + known  Interaction ranges and accuracy  Conditions precision and accuracy cascaded systems  Conditions for > 6 d.o.f., Abbé errors + deformations

Roll simulations 48