Development of cryogenic system in KAGRA

Transcription

1 Development of cryogenic system in KAGRA -Workshop on Gravitational Wave activities in Taiwan- Academia Sinica, Institute of Physics Takafumi Ushiba The University of Tokyo, Japan on behalf of the KAGRA cryogenic subgroup 1

2 KAGRA Cryogenics subgroup Collaborators in Japan Takayuki TOMARU Chief KEK, Assoc. Prof. Nobuhiro KIMURA Cryostat sub-chief KEK, Assoc. Prof. Kazuhiro YAMAMOTO Cryo-Payload sub-chief ICRR, Assist. Prof. Toshikazu SUZUKI Cryostat, Payload KEK, Prof. Rahul KUMAR Simulation, Payload KEK, PD Kieran CRAIG Cryogenic Payload ICRR, PD Takafumi USHIBA Cryogenic Payload U-Tokyo, PD Suguru TAKADA Cryogenics NIFS, Assist. Prof. Collaborators in Taiwan Collaborators in Italy Yuki INOUE Cryogenic Payload AS, PD William CREUS Cryogenic Payload AS, PD Helios VOCCA HCB, Perugia U, Assist. Prof. 2

3 Technicians Shinichi TERASHIMA Machining KEK, Technical Staff Yoshikazu. NAMAI Welding, KEK Technical Staff Ayako UEDA Exp. Assistant, KEK Technical Staff Ayako HAGIWARA CAD KEK, Technical Staff Students Hiroki TANAKA Cryo-Payload, Q ICRR, D1 Takahiro MIYAMOTO Cryo-Payload ICRR, D1 Tomohiro YAMADA Cryo-Payload ICRR, M1 3

4 Overview Interferometer layout Cryogenic payload Cryogenic facility Current progress Summary 4

5 KAGRA gravitational wave detector 3-km arm interferometric gravitational detector. Located at Ikenoya in Japan near Super Kamiokande. Features: -Using underground site -Cooling mirrors 5

6 Interferometer layout of KAGRA Credit: Masaki Ando 6

7 Type-A suspension for KAGRA ETMs 8-stage 14-m suspension for vibration isolation with a cryogenic mirror 14m Suspended from 2 nd floor Type-A suspension: 4-stage GAS room temperature Cryogenic Payload Credit: Masaki Ando 7

8 Cryogenic payload Inside cryostat Room temperature suspension Platform Marionette & Recoil mass Credit: Masaki Ando Cryogenic payload 23 kg sapphire mirror Total mass is 200 kg Control and vibration isolation Cooling with a cryocooler connected to a Platform Mirror & Recoil mass Intermediate mass & recoil mass 8

9 Ultra-low vibration cryocooler This technology was established in CLIO prototype interferometer nm vibration at cold stage comparable vibration level of whole system with Kamioka seismic vibration Commercial Pulse-Tube Cryocooler 3 order Cold Stage Whole System Commercial Pulse-Tube Cryocooler Our system 2 order Our system Credit: Masaki Ando 9

10 Reduction of thermal radiation Thermal radiation is problematic for cooling. Black coating We succeeded to reduce about 1/1000 times thermal radiation heat load from beam openings by using 100K cold tubes with black coating and baffles. Black coating and baffles in cold tube Cryostat 10

11 Cryogenic payload Platform stage: Tilt adjustment and vertical vibration isolation Marionette and recoil mass: Tilt adjustment and displacement control (rough) Intermediate mass and recoil mass: Tilt adjustment and displacement control (precise) Test mass and recoil mass: displacement control (very precise) 11

12 Readiness Frame (Earthquake Stop) ~70% Designing Heat Link Test fabrication done by using 6N Al wires None-magnetism black coating ~70% Testing Actuator & Sensor ~40% Simulation & test Model in Digital System ~30% Simulation & test Platform Under fabrication Marionette One fabricated Three under fabrication Intermediate Mass One fabricated Three under fabrication Mirror Recoil One fabricated Three under fabrication Installation Jigs ~30% Designing Sapphire Suspension -> Details shown later 12

13 Current Status of our development 13

14 Platform design Mirrors for OpLev Base Plate Four platforms are under fabrication now. CuBe Blade Spring Ball screw Moving Mass Mass (Cu) Motor 14

15 Test assembly We have succeeded in test assembly of a metal prototype payload! Fabrication of 1 st cryogenic Payload w/o sapphires and platform has been done. 2 Axis tilting control (Moving Mass) 6 photosensors + 6 coil-magnet actuators (not yet installed) 4 Coil-Magnet actuators (not yet installed) 15

16 Test assembly We have succeeded in a test assembly of metal prototype payload! Fabrication of 1 st cryogenic Payload w/o sapphires and platform has been done. 2 Axis tilting control (Moving Mass) 6 photosensors + 6 coil-magnet actuators (not yet installed) 4 Coil-Magnet actuators (not yet installed) 16

17 Tilt adjustment system ~25mm ~25mm Mass (Cu) Motor Fixed Moving Mass Ball screw 0mm Marionette Intermediate mass Marionette Intermediate mass Laser Mirror Dummy mirror Photo detector 17

18 Tilt adjustment result Moving Range: +/- 15mm 1.6mrad/mm Maximum tilting: +/- 24mrad (Requirement: +/- 3mrad) One step of motor: 0.09 Screw Pitch: 1mm Tilting Resolution: 0.4urad (Requirement: 10urad) We plan to have a cryogenic test in this Febrary. 18

19 Test assembly We have succeeded in a test assembly of metal prototype payload! Fabrication of 1 st cryogenic Payload w/o sapphires and platform has been done. 2 Axis tilting control (Moving Mass) 6 photosensors + 6 coil-magnet actuators (not yet installed) 4 Coil-Magnet actuators (not yet installed) 19

20 Actuator noise estimation Safety factor : 10 TM:1.5mN/A IM:30mN/A MN:50mN/A Low Power Coil Driver (2mA) Parameter: Actuator efficiency : 1.5mN/A Low Power Coil Driver : I MAX = 2mA Noise contribution over 10 Hz is mainly from TM actuators 20

21 Sapphire test mass Top: sapphire blade spring -compensate fiber-length differences Middle: sapphire fibers with nailhead -high thermal conductivity -low thermal noise Bottom: sapphire mirror with ears Bonding method Sapphire fibers & sapphire blade: -indium bonding Spphire fibers & sapphire ears: -indium bonding Sapphire test mass & sapphire ears: -Hydro-catalysis bonding 21

22 Prototype test of HCB Prototype bonding jigs have been fabricated HCB bonding test have been performed Two ears bonded on 23 kg sapphire mass Bonds were left for 4 weeks curing Entire mass was supported only by the ears for 15 days The bonds survived the mirror can be suspended 22

23 Plan of a cryogenic payload assembly We will have minimum test of cryogenic payload in Lab before initial installation. Mechanical strength test Cooling test Control room & cryogenic temperature (1) Test of pendulum -> 1/4 test cryostat in KEK (2) Test of sapphire suspension -> new best size cryostat (3) HCB and assembly of sapphire parts of ETM & ITM -> new clean booth in Toyama Univ. (4) Final assembly of cryo-pay. w/ sapphire -> on site 23

24 Summary The KAGRA cryogenic subgroup is working towords the cryogenic mirror suspension. Mechanical parts design has been almost finished -Only flames are under designing Mechanical parts are under fablication Cooling tests are ongoing A prototype sapphire mass is bonded with the HCB -bonds are strong sufficiently bkagra-phase1 will be operated in March,

25 Thank you for your attention Any questions? 25

26 Supplemental slides 26

27 Sensitivity Curves 27

28 6N Purity Al Heat Link Thermal / Electrical conductivity at cryogenic temperature proportional to material purity. This is important to realize weekly connected heat links to cryogenic payload Stranded cable (made of many thin wires) has advantage to have small spring constant. Teion Kogaku 46, (2011)

29 What is HCB? HCB uses NaOH, KOH or Na 2 SiO 3 solution to bond Can bond silica based material as well as metal oxides Hydroxide catalysis bonding (HCB) was first used by the gravity probe B experiment Operation at 2.5K in UHV HCB also used by Adv. LIGO and Adv. Virgo 29

30 What is HCB? Important point: after bonding, parts essentially become one piece. Cannot separate after bond has set Ear positioning during bonding very important! Bonding surfaces must be very flat in order to achieve strong bond 30