![Page 1: ICRR M2 Takanori Sekiguchi ICRR, NAOJ A, ERI B, Sannio Univ. C, INFN Roma D, NIKHEF E, AEI F Ryutaro Takahashi, Kazuhiro Yamamoto, Takashi Uchiyama, Hideharu](https://reader035.vdocuments.net/reader035/viewer/2022062308/56649da35503460f94a8fca0/html5/thumbnails/1.jpg)
Performance Measurement of the
Prototype Pre-isolator for KAGRA-SASICRR M2 Takanori Sekiguchi
ICRR, NAOJA, ERIB, Sannio Univ.C, INFN RomaD, NIKHEFE, AEIF
Ryutaro Takahashi, Kazuhiro Yamamoto, Takashi Uchiyama, Hideharu IshizakiA, Akiteru TakamoriB, Riccardo DeSalvoC, Ettore
MajoranaD, Eric HennesE, Jo van den BrandE, Alessandro BertoliniE,F, Masatake Ohashi, Kazuaki Kuroda, LCGT Collaboration
JGW-G1200930
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Role of Pre-Isolator
2012/3/24The 67th Annual Meeting of
JPS2
Top part of KAGRA-SAS
Pre-Isolator
1. Vibration Isolation at a low frequency (< 0.1 Hz)
* Attenuate the mirror oscillation at the micro-seismic peak (0.2~0.3 Hz)
2. Control the position and orientation of the system
Role of Pre-isolator
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Schematic View of Pre-Isolator
2012/3/24The 67th Annual Meeting of
JPS3
GAS Filter・ Vertical attenuation
Inverted Pendulum・ Horizontal attenuation
Position Sensor (LVDT)
Coil-magnet actuator
~1.2 m
Accelerometer
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Pre-Isolator Prototype
2012/3/24The 67th Annual Meeting of
JPS4
GAS Filter
Inverted Pendulum
@Kashiwa, ICRR
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About this Presentation
2012/3/24The 67th Annual Meeting of
JPS5
Performance measurement of GAS Filter, vertical LVDT, coil-magnet actuator
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Geometric Anti-Spring (GAS) Filter
2012/3/24The 67th Annual Meeting of
JPS6
Radially arranged cantilever springs
The horizontal force works as an anti-spring and reduces the resonant frequency of the filter
In principle the frequency can be reduced to zero.
Restoring force
Anti-springforce
Compression
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Resonant Frequency Measurement
2012/3/24The 67th Annual Meeting of
JPS7
The resonant frequency of the filter is measured, tuning the load weight and the blade compression.
Using Mercury 2000 (MicroE systems) as a displacement sensor
Load
~320 kg
Photo sensor
Scale
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Resonant Frequency Measurement
2012/3/24The 67th Annual Meeting of
JPS8
Load Increases
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LVDT (Linear Variable Differential Transducer)
2012/3/24The 67th Annual Meeting of
JPS9
Non-touching displacement sensor
10 kHz modulation
The voltage induced at the two receiver coils depends on the position of the primary coil.
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LVDT Calibration
2012/3/24The 67th Annual Meeting of
JPS10
Micrometer
Res
idu
al [
mV
]
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LVDT Noise Spectrum
2012/3/24The 67th Annual Meeting of
JPS11
~100 nm/rtHz @ 1 - 50 Hz
As sensitive as TAMA-LVDT
Limited by the noise from the electric circuit (driver)
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Force Transfer Function
2012/3/24The 67th Annual Meeting of
JPS12
LVDT
Coil-Magnet Actuator
∝f-2
Random input signal to the actuator
Transfer function from the actuation force to the LVDT signal
With the digital system
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Non-Linear Response
2012/3/24The 67th Annual Meeting of
JPS13
Actuator Input Signal
LVDT Output
When the actuator is driven by a high frequency signal (> 2 Hz), the LVDT shows a non-linear response.
The same phenomenon is observed even when the magnet for the actuator is eliminated.
Magnetic field couplings??
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Summary, Future Works
2012/3/24The 67th Annual Meeting of
JPS14
Performance measurement on the GAS filter, LVDT and actuator of the pre-isolator prototype
The top filter can be tuned at ~ 0.2 Hz, and maybe even lower. The linear signal is observed in LVDT over a range of ~1 cm. Non-linear couplings between the actuator and LVDT.
Tuning the top filter at lower than 0.1 Hz, and the Q-factor, hysteresis, stability are checked.
Investigating the cause of the actuator-LVDT couplings Control test with the inverted pendulums
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END
2012/3/24The 67th Annual Meeting of
JPS15
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APPENDIX
2012/3/24The 67th Annual Meeting of
JPS16
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Q-factor Measurement
2012/3/24The 67th Annual Meeting of
JPS17
Chunk 1Chunk 2
Chunk 3
Chunk 4
Divide a ring-down signal to many chunks. The signal in each chunk is fit by the following function
)2sin()/exp( 0 fttAy
Investigating amplitude (A) dependence of the Q-factor (Q=π*f*τ)
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Q-factor Measurement
2012/3/24The 67th Annual Meeting of
JPS18
Q-factor increases when the amplitude decreases
Explained by the dissipation controlled by Self-Organized Criticality (SOC)
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Displacement Sensor
2012/3/24The 67th Annual Meeting of
JPS19
Linear encoder Mercury 2000 (Micro E systems) Resolution: 80 nm
Photosensor
Scale
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Force Transfer Function
2012/3/24The 67th Annual Meeting of
JPS20