Ryutaro TakahashiRyutaro Takahashi(National Astronomical Observatory of Japan)(National Astronomical Observatory of Japan)
Vibrtion isolation system fVibrtion isolation system for KAGRAor KAGRA
The 6th Korea-Japan workshop on KAGRANAOJ, 20-21 June, 2014
ContentsContents
1.1. ConfigurationConfiguration
2.2. R&D StatusR&D Status• Test of the payload prototypeTest of the payload prototype• Test of the bottom filter prototypeTest of the bottom filter prototype
3.3. SummarySummary
1. Configuration
Top Filter (TF)
Inverted Pendulum (IP)
Standard Filter (SF)Filter1~3 in Type-AFilter1 in Type-B
Bottom Filter (BF)
Test Mass (TM)Recoil Mass (RM)
Pre-isolator (PI)
Payload (PAY)
Filter chain
Intermediate Mass (IM)Intermediate Recoil Mass (IRM)
Seismic AttSeismic Attenuation Syenuation Sy
stemstemSASSAS
(Type-A/B)(Type-A/B)
Overview of KAGRA Vibration Isolation System
Type-A: for cryogenic mirrorsType-B: for room temperature mirrorsType-Bp: simpler Type-BType-C: for small optics
Type-A
CRY-PAY
IP
SF
TF
BF
Type-BType-B
Outer frame
IP
SF
PAY
BB
TF
BF
Type-Bp
SF
PAY
BB
BF
BP
Type-C
Stack
BP
BB
•Test of the pre-isolaor prototype was finished in Kashiwa (ICRR).
•Test of the payload prototype is under going in Mitaka (NAOJ).
•Test of the bottom filter prototype was finished in Mitaka (NAOJ-ATC)
•Full prototype test using TAMA300 will be started.
2. R&D Status
Test of the payload prototype
•Main parts were assembled once to confirm the dimensions each other.•Transfer functions of TM-RM system was measured.•Position sensors are tested and improved.
TM
RM
IM
60 cm
Intermediate mass (IM) was fixed to a frame, suspending:
• Test mass (mTM = 10.7 kg) by Tungsten wires (d = 0.2 mm)
• Recoil mass (mRM = 20.4 kg) by Tungsten wires (d = 0.6 mm)
Control the TM by 4 Optical Sensor and Electro-Magnetic actuators (OSEMs).
OSEMs were diagonalized to the virtual directios (x, pitch, yaw)
Test mass (TM) and Recoil mass (RM)
60 cm
Transfer function of the TM-RM
by J. V. van Heijningen
The legend describes the position of the flag alongthe optic axis.
The sensitivities were calculated from the slope of each curve.
PhotodiodeLED
The horizontal axis describes the position of the flag as it
moves either in or out of the OSEM.
Calibration of OSEM
by F. E. Pena Arellano
Flag misalignment ( mm ) Slope ( V / mm ) Error (%) R
1.00 -6.296 -13.8 0.9970.500 -6.746 -7.6 0.996
0.250 -6.948 -4.9 0.9960.000 -7.304 0.0 0.996-0.250 -7.323 0.3 0.996-0.500 -7.630 4.5 0.996
When using the calibration calculated at the middle plane, this OSEM offers a 5% error
within the range [ - 0.500 , + 0.250 ] mm along the optic axis.
In the linear range of each curve a straight line was fitted.
• Number of data points: 9
• Measurement range: [ - 0.400 , + 0.400 ] mm from the
centre (9 mm in the scale of this example).
Calibration of OSEM
by F. E. Pena Arellano
Test of the bottom filter prototype
Function: final vertical filterDimension: 730 x 272hWeight: 99kgBlades: Marasing steel x3Load: 48.6kgAimed frequency: 0.4Hz
One vertical position sensor: LVDTOne vertical actuator: voice coilAttitude control: two motors for pitch,
one motor for yaw
Aging process•Daido Steel MAS-1: 480 , 4h℃•Aubert & Duval Marval 18: 435 , 100h℃
Maraging steel for GAS blade
G&M ATCOptimum load [kg] 47.6 50.2 (5% up)Working height [mm] 64.5 64.5Frequency [Hz] 0.4 0.7→0.3
Measurement of resonant frequencies
Four kinds of vibration isolation system are used in KAGRA.
The OSEMs on RM were diagonalized and the transfer functions of TM-RM system were measured.
The new optics in the OSEM offered 5% error in the range of 0.75mm.
The production process of the GAS blade was estblished with new maraging steel and shorter aging time.
3. Summary