Hard or Soft ?

C. Collette, K. Artoos, S. Janssens, P. Fernandez-Carmona, A. Kuzmin, M. Guinchard, A. Slaathaug, C. Hauviller

The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD

IWLC2010 International Workshop on Linear Colliders 2010

Hard or Soft …active isolators to stabilize the main beam quadrupoles of the CLIC ?

C. Collette, K. Artoos, S. Janssens, P. Fernandez-Carmona, A. Kuzmin, M. Guinchard, A. Slaathaug, C. Hauviller

The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD

IWLC2010 International Workshop on Linear Colliders 2010

Ground motion in the LHC tunnel

Isolators need to reduce the transmission of the ground vibrations by roughly a factor 5 between 1Hz and 20 Hz

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C. Collette, IWLC10, Geneva, 21 October 2010

Outline

C. Collette, IWLC10, Geneva, 21 October 2010

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Passive vibration isolation Active vibration isolation Soft active support vs stiff active support CLIC quadrupole stabilization

Passive isolation

Trade off between magnification at resonance and isolation

Isolation

C. Collette, IWLC10, Geneva, 21 October 2010

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C. Collette, IWLC10, Geneva, 21 October 2010

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Relaxation isolator

Optimal parameters

Relaxation

Soft support :(i) Improves the isolation(ii) Make the payload more sensitive to external forces Fa

Effect of the support stiffness7

C. Collette, IWLC10, Geneva, 21 October 2010

Dynamic vibration absorber

C. Collette, IWLC10, Geneva, 21 October 2010

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• Spurious peaks• Difficult to make an efficient compact design Either damping, or isolation for narrow band excitation

1909: US 970,368

Anti-resonant isolators

C. Collette, IWLC10, Geneva, 21 October 2010

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Isolation from narrow band excitation, e.g. rotor

1934: US 1,973,510

Feedback control principle

Add virtual mass(e.g. space applications)

Feedback control principle

Sky-hook damper (D.C. Karnopp, 1969)

Feedback control principle

Position feedback would be great ! How to measure it ?

C. Collette, IWLC10, Geneva, 21 October 2010

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Inertial reference on payload

2009: Lithography WO 084,966 A1

1957: Seismometer US 2,776,560

C. Collette, IWLC10, Geneva, 21 October 2010

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Inertial reference on ground

2007: US 2007/003,5074 A1

C. Collette, IWLC10, Geneva, 21 October 2010

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Two stages

1994: Proc. SPIE vol. 2264

Passive vs Active vibration isolation

Only active isolation can provide both:

- Isolation in a broad frequency range between 1Hz and 20 Hz

- Dynamic stiffness for robustness to disturbances and compatibility with alignment

Conditions:

- Measure the vibrations

- Process the signal in real time

- Apply small dynamic forces

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C. Collette, IWLC10, Geneva, 21 October 2010

Comparison

Very Soft (1 Hz) Stiff (200 Hz)

• Pneumatic actuator• Hydraulic actuator

+ Broadband isolation- Stiffness too low- Noisy

• Electromagnetic in parallel with a spring• Piezo actuator in series with soft element (rubber)

COMPARISON

+ Passive isolation at high freq.+ Stable- Low dynamic stiffness- Low compatibility with alignment and AE

Soft (20 Hz)

• Piezoelectric actuator in series with stiff element (flexible joint)

+ Extremely robust to forces+ Fully compatible with AE+ Comply with requirements- Noise transmission- Strong coupling

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C. Collette, IWLC10, Geneva, 21 October 2010

Error budgeting

No significant difference in the noise transmission

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C. Collette, IWLC10, Geneva, 21 October 2010 Noise reduction

Strong coupling19

C. Collette, IWLC10, Geneva, 21 October 2010

Stability Performances

Objective

Stability of slender quadrupoles

Frobenius norm:

Vertical transmissibilities

C. Collette et al, Nucl. Instr. meth. in phys. Res. A, vol.621 (1-3) pp.71-78 (2010).

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C. Collette, IWLC10, Geneva, 21 October 2010

Conclusions and future work

C. Collette, IWLC10, Geneva, 21 October 2010

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Active control can improve the isolation at low frequency without enhanced sensitivity to disturbances.

Main concepts presented on one d.o.f. systems. Stiff and soft active supports provide similar

stabilization at low frequency. Stiff active supports successfully applied for

the stabilization CLIC quadrupoles. Performances will be improved with a more

adapted sensor (under development).