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

• n behalf of the KAGRA cryogenic subgroup

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KAGRA Cryogenics subGroup

Toshikazu SUZUKI

Cryostat, Payload KEK, Prof.

Nobuhiro KIMURA

Cryostat sub-chief KEK, Assoc. Prof.

Kazuhiro YAMAMOTO

Cryo-Payload sub-chief ICRR, Assist. Prof.

Takayuki TOMARU

Chief KEK, Assoc. Prof.

Rahul KUMAR

Simulation, Payload KEK, PD

Suguru TAKADA

Cryogenics NIFS, Assist. Prof.

Kieran CRAIG

Cryogenic Payload ICRR, PD

Takafumi USHIBA

Cryogenic Payload U-Tokyo, PD

Helios VOCCA

HCB, Perugia U,

• Assist. Prof.

Yuki INOUE

Cryogenic Payload AS, PD

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Collaborators in Japan Collaborators in Taiwan Collaborators in Italy

William CREUS

Cryogenic Payload AS, PD

Ayako HAGIWARA

CAD KEK, Technical Staff

Shinichi TERASHIMA

Machining KEK, Technical Staff

Ayako UEDA

• Exp. Assistant, KEK

Technical Staff

• Yoshikazu. NAMAI

Welding, KEK Technical Staff

Technicians

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Hiroki TANAKA

Cryo-Payload, Q ICRR, D1

Takahiro MIYAMOTO

Cryo-Payload ICRR, D1

Tomohiro YAMADA

Cryo-Payload ICRR, M1

Students

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

Overview

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KAGRA gravitational wave detector

• 3-km arm interferometric gravitational detector.
• Located at Ikenoya in Japan near Super Kamiokande.
• Features:

－Using underground site －Cooling mirrors

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Credit: Masaki Ando

Interferometer layout of KAGRA

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Credit: Masaki Ando

Type-A suspension for KAGRA ETMs

14m

Cryogenic Payload Type-A suspension:

4-stage GAS filters @ room temperature Suspended from 2nd floor

8-stage 14-m suspension for vibration isolation with a cryogenic mirror

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Credit: Masaki Ando

Cryogenic payload

Inside cryostat

Cryogenic payload

Platform Marionette & Recoil mass Mirror & Recoil mass Room temperature suspension Intermediate mass & recoil mass

• 23 kg sapphire mirror
• Total mass is 200 kg
• Control and vibration isolation
• Cooling with a cryocooler

connected to a Platform

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Credit: Masaki Ando

Ultra-low vibration cryocooler

Cold Stage Whole System

3 order 2 order

Our system Commercial Pulse-Tube Cryocooler Commercial Pulse-Tube Cryocooler Our system

• nm vibration at cold stage
• comparable vibration level of

whole system with Kamioka seismic vibration

This technology was established in CLIO prototype interferometer

Reduction of thermal radiation

Black coating

Thermal radiation is problematic for cooling.

Cryostat Black coating and baffles in cold tube

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.

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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)

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Readiness

Sapphire Suspension

• > Details shown later

Mirror Recoil

• One fabricated
• Three under

fabrication Intermediate Mass

• One fabricated
• Three under

fabrication Marionette

• One fabricated
• Three under

fabrication Platform

• Under fabrication

Frame (Earthquake Stop) ~70%

• Designing

Heat Link

• Test fabrication done

by using 6N Al wires None-magnetism black coating ~70%

• Testing

Installation Jigs ~30%

• Designing

Actuator & Sensor ~40%

• Simulation & test

Model in Digital System ~30%

• Simulation & test

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Current Status of our development

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Platform design

Base Plate CuBe Blade Spring Moving Mass Mirrors for OpLev

Motor Mass (Cu) Ball screw

Four platforms are under fabrication now.

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Test assembly

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

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Test assembly

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

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Tilt adjustment system

Motor Mass (Cu) Ball screw ~25mm ~25mm 0mm

Intermediate mass

Marionette

Mirror Fixed Moving Mass

Marionette Intermediate mass Dummy mirror Laser Photo detector

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Tilt adjustment result

1.6mrad/mm

Moving Range: +/- 15mm 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.

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Test assembly

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

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Actuator noise estimation

TM：1.5mN/A IM：30mN/A MN：50mN/A Low Power Coil Driver （2mA） Noise contribution over 10 Hz is mainly from TM actuators

Parameter: Actuator efficiency : 1.5mN/A Low Power Coil Driver : IMAX = 2mA

Safety factor : 10

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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

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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
• nly by the ears for 15 days
• The bonds survived

→the mirror can be suspended

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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

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• 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.

Summary

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Thank you for your attention Any questions?

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Supplemental slides

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Sensitivity Curves

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6N Purity Al Heat Link

Teion Kogaku 46, (2011) 415-420

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.

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What is HCB?

• HCB uses NaOH, KOH or Na2SiO3 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

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What is HCB?

• Important point: after bonding, parts essentially become
• ne 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

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