Vibration Control Using a Dedicated Inertial Sensor
Résumé
The Compact Linear Collider (CLIC) project is right in the development phase. In this prospect, the main objective of the final focus stabilization is to succeed in damping ground motion vibration at the sub-nanometer scale to avoid any unwanted motion of the two last final focus magnets. Active vibration control using high-resolution industrial seismic sensors has already shown its limits in the desired range of attenuation [4-100] Hz. Hence, a dedicated inertial sensor has been designed, tuned to fit CLIC requirements. It doesn't contain any feedback or coil which would linearize its dynamic in its bandwidth [0.1-100] Hz, avoiding electrical noise or thermal noise, and when used for active control, enhancing its performances thanks to the internal resonance. An analytical modeling of the sensor dynamic behavior also shown experimentally gives a first internal resonance around 11 Hz. This paper is complemented by a comparative measurement with high precision industrial sensors. A noise level 2.5 times better (0.04 nm at 4 Hz) has been achieved. This sensor has also been tested in the context of vibration rejection with a sub-nanometer active vibration rejection support. Experimental results have been compared with the one obtained with the state-of-the-art industrial sensors. Vertical seismic motion attenuation results have shown unprecedented performances. A damping ratio of 8.5 has been achieved at 4 Hz, leading to an rms displacement of the support of 0.25 nm thanks to the active support prototype and the dedicated sensor.
Mots clés
Vibrations
Bandwidth
Noise measurement
Seismic measurements
Resonant frequency
Mechanical sensors
damping
motion control
sensors
stability
vibration control
vibration measurement
vertical seismic motion attenuation
subnanometer active vibration rejection support
vibration rejection
thermal noise avoidance
electrical noise avoidance
coil
high-resolution industrial seismic sensor
active vibration control
damping ground motion vibration
final focus stabilization
CLIC project
compact linear collider project
dedicated inertial sensor
frequency 4 Hz to 100 Hz
Control
inertial sensor
vibration
seismic motion
noise
magnet
final focus
magnet: stability
performance
CERN CLIC
magnet: oscillation
mechanical engineering
oscillation
numerical calculations