Download Vibration isolation system for KAGRA

Vibrtion isolation system
for KAGRA
Ryutaro Takahashi
(National Astronomical Observatory of Japan)
The 6th Korea-Japan workshop on KAGRA
NAOJ, 20-21 June, 2014
Contents
1.
Configuration
2.
R&D Status
• Test of the payload prototype
• Test of the bottom filter prototype
3.
Summary
1. Configuration
Seismic
Attenuation
System
SAS
(Type-A/B)
Top Filter (TF)
Pre-isolator
(PI)
Filter chain
Inverted Pendulum (IP)
Standard Filter (SF)
Filter1~3 in Type-A
Filter1 in Type-B
Bottom Filter (BF)
Intermediate Mass (IM)
Intermediate Recoil Mass (IRM)
Payload
(PAY)
Test Mass (TM)
Recoil Mass (RM)
Overview of KAGRA Vibration Isolation System
Type-A: for cryogenic mirrors
Type-B: for room temperature mirrors
Type-Bp: simpler Type-B
Type-C: for small optics
Type-A
TF
IP
SF
BF
CRYPAY
Type-B
TF
IP
SF
BF
PAY
BB
Outer frame
Type-Bp
SF
BF
PAY
BB
BP
Type-C
BB
Stack
BP
2. R&D Status
•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.
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.
Test mass (TM) and Recoil mass (RM)
IM
60 cm
RM
60 cm
Intermediate mass (IM) was fixed to a frame, suspending:
• Test mass (mTM = 10.7 kg) by Tungsten wires (d = 0.2 mm)
TM
• 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)
Transfer function of the TM-RM
by J. V. van Heijningen
Calibration of OSEM
The horizontal axis describes the position of the flag as it
moves either in or out of the OSEM.
LED
Photodiode
The legend describes the position of the flag along
the optic axis.
The sensitivities were calculated from the
slope of each curve.
by F. E. Pena Arellano
Calibration of OSEM
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).
Flag misalignment ( mm )
Slope ( V / mm )
Error (%)
R
1.00
0.500
-6.296
-6.746
-13.8
-7.6
0.997
0.996
0.250
0.000
-0.250
-0.500
-6.948
-7.304
-7.323
-7.630
-4.9
0.0
0.3
4.5
0.996
0.996
0.996
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.
by F. E. Pena Arellano
Test of the bottom filter prototype
Function: final vertical filter
Dimension: f730 x 272h
Weight: 99kg
Blades: Marasing steel x3
Load: 48.6kg
Aimed frequency: 0.4Hz
One vertical position sensor: LVDT
One vertical actuator: voice coil
Attitude control: two motors for pitch,
one motor for yaw
Maraging steel for GAS blade
Aging process
•Daido Steel MAS-1: 480℃, 4h
•Aubert & Duval Marval 18: 435℃, 100h
Measurement of resonant frequencies
Optimum load [kg]
Working height [mm]
Frequency [Hz]
G&M
47.6
64.5
0.4
ATC
50.2
(5% up)
64.5
0.7→0.3
3. Summary
 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.