Development of cryogenic system in KAGRA -Workshop on Gravitational - PowerPoint PPT Presentation

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

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

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

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

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

Interferometer layout of KAGRA 6 Credit: Masaki Ando

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

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

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 Whole System Cold Stage Commercial Pulse-Tube Cryocooler 3 order 2 order Our system Our system 9 Credit: Masaki Ando

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. Cryostat Black coating and baffles in cold tube 10

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

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

Current Status of our development 13

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

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

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

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

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

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

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

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

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

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 test @ 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

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, 2018. 24

Thank you for your attention Any questions? 25

Supplemental slides 26

Sensitivity Curves 27

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) 415-420 28

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

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