1. CLIC magnets precise positioning

2. 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

3. 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

4. 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 1 Hz
Nano-positioning
Sensor: Linear encoder
Positioning time:  20 ms
Displacement steps: 10 up to 50 nm
D. Tshilumba, CERN, 10 November 2016

5. 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 1Hz (vertical)
5nm 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

6. 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

7. 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

8. 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

9. Active Isolation Strategies9
Acceleration Feedback
Feedback control principle
Add virtual mass
D. Tshilumba, CERN, 10 November 2016

10. Active Isolation Strategies10
Velocity Feedback
Feedback control principle
Magneto rheological fluids
Sky-hook damper
(D.C. Karnopp, 1969)

11. Active Isolation Strategies11
Position Feedback
Feedback control principle
Position feedback would be great !
D. Tshilumba, CERN, 10 November 2016

12. 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

13. 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

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

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

16. 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

17. 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

18. Thank you for your attention!18

19. 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

20. 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

21. 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

22. 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

23. 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