hard or soft ? c. collette, k. artoos, s. janssens, p. fernandez-carmona, a. kuzmin, m. guinchard,...
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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
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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
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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
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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).