CLIC magnets precise positioning

Compact Linear Collider (CLIC) 𝑒 − ∅ 5.6 𝑚 𝑒 + 48km Complementary to LHC Linear collider  avoid synchrotron radiation ( ∆ 𝐸 𝑏 ∝ 𝐸 𝑏 4 ( 𝑚 4 𝑅) ) Vert. Beam size 1nm at IP Hor. Beam size 40 nm at IP Challenges: Beam emittance preservation  Alignment of components  Quadrupole magnet stability D. Tshilumba, CERN, 10 November 2016

CLIC Main Beam Quadrupoles Quadrupole magnets Mass 100 – 400 kg Length 500 – 2000 mm Field gradient 200 T/m Common Basic principle: Lorentz Force 𝐹 =𝑞 𝑣 × 𝐵 Functions To Focus the beam To steer the beam : “Nano-positioning” Courtesy of J. Pfingstner D. Tshilumba, CERN, 10 November 2016

Magnets position control architecture Linac Feedback Sensor: Beam position monitor Bandwidth:  1Hz Interaction point Feedback Sensor: Beam Position Monitor Bandwidth: < 1 Hz Stabilization Sensor: Inertial sensor (Geophone) Bandwidth:1  50 Hz Stability requirement: 1.5 nm rms @ 1 Hz Nano-positioning Sensor: Linear encoder Positioning time:  20 ms Displacement steps: 10 up to 50 nm D. Tshilumba, CERN, 10 November 2016

Magnet positioning system Long range positioning stage requirements Functions : 5dofs Alignment (before beam) 2dofs Nanopositioning (beam-based alignment phase + nominal beam operation phase) 2dofs Vibration compensation (nominal beam operation phase) Stability requirements: 1.5nm rms @ 1Hz (vertical) 5nm rms @ 1 Hz (lateral) Parameters Value Resolution <0.25nm step displacement 10 up to 50nm Stroke ± 3mm Pitch angle 6rad Yaw angle Roll angle Max 100rad Speed  50μm/s Settling time t1->t2 10ms≤ts≤15ms On-axis stiffness (vertical/lateral) 400 N/μm Force capacity (positioning) 5N+20N Force capacity (stabilization) 10N Study of an integrated positioning system with high stiffness (>100N/m) capable of moving heavy loads (>50 kg) with high resolution (<1nm) over a large range (≥1mm) No actuator available on the market D. Tshilumba, CERN, 10 November 2016

Vibration Isolation Strategies Earth quake protection Big Physics projects Big Physics projects Space Daily life Big civil engineering projects D. Tshilumba, CERN, 10 November 2016

Vibration Isolation Spring mass system Basics Term Sym. Unit mass m [kg] stiffness k [N/m] Damping c [N/(m/s)] Induced force Fa [N] Ground vibrations w [m] Quadrupole vibrations x Term Physical meaning Symbol Unit Transmissibility x/w Twx [-] Compliance x/Fa TFax [m/N] Both can be referred to as transfer functions

Vibration Isolation Effect of support stiffness Soft support : Basics Effect of support stiffness [m/N] Watercooling Accoustics Ventilation Transmissibility Compliance Soft support : Improves the isolation Make the payload more sensitive to external forces Fa D. Tshilumba, CERN, 10 November 2016

Active Isolation Strategies 9 Acceleration Feedback Feedback control principle Add virtual mass D. Tshilumba, CERN, 10 November 2016

Active Isolation Strategies 10 Velocity Feedback Feedback control principle Magneto rheological fluids Sky-hook damper (D.C. Karnopp, 1969)

Active Isolation Strategies 11 Position Feedback Feedback control principle Position feedback would be great ! D. Tshilumba, CERN, 10 November 2016

Active Isolation Strategy Concept demonstration with staged test benches Collocated pair EUCARD deliverable Type 1 Seismometer FB max. gain +FF (FBFFV1mod): 7 % luminosity loss (no stabilisation 68 % loss) X-y proto

Magnet positioning system Stabilization / Nano-positioning prototype setup Piezo stack actuators Resolution: 0.15 nm Stiffness : 480 N/m Stroke: 15 µm Blocking force: 12.5 kN Optical encoder Resolution: < 1 nm Magnet mass: 80kg D. Tshilumba, CERN, 10 November 2016

Condensed type1 bench MIMO model Assembly dynamics extraction 1 4 2 3 D. Tshilumba, CERN, 10 November 2016 14

Condensed type1 bench MIMO model Assembly dynamics extraction D. Tshilumba, CERN, 10 November 2016 15

Condensed type1 bench MIMO model Coupled inputs and Outputs In(1): front left leg In(2): front right leg In(3): back left leg In(4): back right leg Out(1): front lateral encoder Out(2): front vertical encoder Out(3): back lateral encoder Out(4): back vertical encoder Interactive MIMO system 𝐺(𝑠) Controller design of 𝐶(𝑠) Improve reference tracking Decrease I/O interaction Highly coupled system Decoupling and decentralized control required 16

Condensed type1 bench MIMO model Closed loop reference tracking In(1): reference signal 1 In(2): reference signal 2 In(3): reference signal 3 In(4): reference signal 4 Out(1): front lateral encoder Out(2): front vertical encoder Out(3): back lateral encoder Out(4): back vertical encoder SVD-controller MIMO system 𝐺 𝑐𝑙 (𝑠) 𝐺 𝑐𝑙 (𝑠)= 𝐶 𝑠 𝐺(𝑠) 𝐼 𝑠 +𝐶 𝑠 𝐺(𝑠) Decoupling by Singular value decomposition -Controller design on decoupled diagonal MIMO system -Come back to original coordinates -Off- diagonal always < 1 17

Thank you for your attention! 18

Direct drive XY stages Parametric modelling CAD NEXUS CATIA V5 CAD parameters exchange and bi-directional update Input parameters: Remote magnet displacement (P2) Notch hinges thicnkess (P4) Diameter pillar (P5) Fillet radius pillar (P6) Notch hinges depth (P7) Output parameters: Equivalent Max stress (P1) First eigen frequency (P3) Vertical magnet displacement (P8) CAD NEXUS CATIA V5 ANSYS WB Powerful tool for automatized sensitivity and optimisation study D. Tshilumba, CERN, 20 April 2016

Direct drive XY stages Parametric modelling: Sensitivity study Lowest eigen frequency to P4 and P5 Larger diameter  larger frequency increase in a fixed interval of notch thickness Assymptotic limit of diameter contribution to the frequency Local maximum for a fixed diameter value

Magnet positioning system Current system overview Magnet mass: 80kg Limitations: insuficient stroke of fine stage for thermal load compensation in tunnel ( >100 µm) Limited precision of coarse stage (1 µm achievable after several iterations) ~50 days of operation using fine stage only Coarse stage (cams) locked after pre-alignment Resolution : 0.35µm Stroke: 3mm Fine stage (piezo stacks) Resolution: 0.15nm Stiffness : 480N/m Useful Stroke: 10 µm Upgrade of existing type 1 module Alternative concept for long range actuator

Magnet positioning system Nano-positioning: Inter-pulse sequence t1 t2 20 Time (ms) 1 2 3 4 Stage Beam divided into trains Calculation of new positions by global controller Positioning step of magnet check of actual displacement (machine protection) D. Tshilumba, DSPE Conference, 04 October 2016

Previous work: vibration isolation Stability requirements: Vertical: 1.5 nm (rms) at 1 Hz Horizontal: 5 nm (rms) at 1 Hz 1 d.o.f. (membrane) 2 d.o.f. (xy-guide) Type 1 Water-cooled magnet D. Tshilumba, Delft, 15 April 2015