1. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Refrigerator and Cryostat Design for LCGT N. KIMURA A, T. SUZUKI A, S. KOIKE B, T. KUME B, T. OHMORI D, K. SASAKI A, Y. SAITO C, Y. SATO C, H. YAMAOKA C and LCGT Collaboration A Cryogenics Science Center/KEK B Mechanical Engineering Center/KEK C Accelerator Laboratory/KEK D Teikyo University KEK: High Energy Accelerator Research Organization

2. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA 2 Outline LCGT cryogenics Cooling option for the Mirror Thermal Analysis Mechanical Analysis Materials (New MLI for LCGT) Summary

3. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Main beam (1200mm FL) to SAS View ports Remote valve Low vibration cryocooler unit Main LASER beam  2.4m ~3.8m Cryostat Stainless steel t20mm Diameter 2.4m Height ~3.8m M ~ 10 ton Cryocoolers Pulse tube, 60Hz 0.9 W at 4K (2nd) 36 W at 50K (1st) Drawn by S. Koike (KEK) Cryostat with four cryocooler units Structure of Mirror Cryostat

4. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Basic requirements from the LCGT cryogenics Temperature of the test mass/mirror : 20 [K] Inner radiation shield have to be cooled to < 8 K Cool the mirror without introducing excess noise, especially vibration due to cryo-coolers. Easy access and enough space for installation work around the mirror. Satisfy ultra high vacuum specification < 10 -7 Pa I was requested make a design for the LCGT cryostat from ICRR just One year ago! ISSUES Estimated by Dr. Uchiyama (ICRR)

5. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Cooling Option Vibration Reduction Stage Heat Link VRS Cold Stage Our decision: Use CLIO type Cryo-cooler with low vibration mount for LCGT

6. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Advantage and Disadvantage of CLIO type cryocooler unit Advantage Basic concept of design has been established since the R&D done in CLIO. (2001~2003) Disadvantage Some critical components are unavailable today. Reasons are in the followings. ◦ Withdrawal business by social condition ◦ A change of generation of experienced workers ◦ Replace or renewal of the equipment of a factory We have to find substitutes! Disappeared Items Ready to use Cryo-Cooler equipped special cold stage, such as CLIO type Aluminum FRP tube as anti-vibration support rods High pure aluminum thin wire less than  0.12 mm for heat link. Substitutes for the Items Attach new design of cold stage flanges to mass-produced 1W/4K PTC Replace to Carbon FRP tube as anti-vibration support rods (stiffness AFRP > CFRP > GFRP) Start R&D work with new company for development of high pure aluminum thin wire less than  0.12 mm.

7. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Other Candidate => re-condensation cryo-cooler  Field quality is sensitive to relative position btw yoke and coil  random & individual vibration due to mechanical resonance -> disturb uniform field It needed more R&D worker than to find substitutes materials for the new CLIO type cryo-cooler, when the project was started. Example; SCGR meter, g-2 project at J-PARC The g-2 SC magnet is required with very high magnetic field uniformity below the level of 0.1 ppm.

8. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA 8 An Estimated Break Down List of Thermal Budget Outer Shield (W) ◦ Eleven View Ports 22 ◦ Radiation From 300 K 70 ◦ Support post and Rods 24 ◦ Electrical wires 3 x 10 -4 Total 116 W/unit 29 Inner Shield (W) ◦ Duct Shields* < 0.05 (Beam and SAS) ◦ Eleven View Ports 0.4 ◦ Radiation From 80 K 2.2 ◦ Support post and Rods 2.4 ◦ Electrical wires 3 x 10 -4 ◦ Mirror Deposition 0.9 ◦ Scattering Light ? Total5.9 W/unit1.5 *Heat Load of Duct Shields was presented by Mr. Sakakibara on Monday. 1 st Cold stage2 nd Cold stage

9. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA 9 Estimated Thermal Budget Estimated Heat Loads at the radiation shields and Support posts and rods 70 W by the radiation at 80 K outer shield 2.2 W by the radiation at 8 K inner shield 24 W by the radiation and conduction (support posts and tension rods) at 80 K 2.4 W by the radiation and conduction (support posts and tension rods) at 8 K Low Vibration Cryo-cooler unit Very High Purity Aluminum Conductor (5N8)

10. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA 40,000 W/m/K @ 6K 6N Aluminum 2N Aluminum ~Type A-1070 Example of Thermal Conductivity of 6N-class Very High Pure Aluminum* For inner shield For outer shield 5N up Al RRR=3000 We must put the right material in the right position. Cost: 5N8 > 2N Aluminum

11. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA 11 Estimated Thermal Budget Estimated Heat Loads at the radiation shields and Support posts and rods < 8 K at Connection point with IM dT 2nd =0.5 K 94 K at the top of the 80 K outer shield (A1070) 7.4 K at the top of the 8 K inner shield (5N8+A1070) 47 K at 1 st cold stage of Cryo-cooler 6.5 K at 2nd cold stage of Cryo- cooler dT 1st = 26 K

12. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA *PTC: Pulse Tube-type Cryocooler *PTC: Pulse Tube-type Cryocooler dQ=2 W 5W/50W 4W/40W Heat load/Unit= 400 kW * 20 ppm / 4 units = 2 W/unit Rough Estimation of the PTC* operation with 20 ppm deposition by Scattering Light at 400 kW 20 ppm deposition may be accepted, but we lost contingency cooling power of 2 W. 11 K 23 K

13. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Doors for access to inside Inner shield S. Koike Outer shield W 1600 mm X h 1900 mm W 1020 mm X h 1600 mm

14. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Static deformation analysis Main vacuum duct and the duct to SAS are not connected. Boundary conditions ◦ periphery of the bottom : fix S.Koike

15. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Modal analysis Resonance Frequency S.Koike Boundary condition: fix the perimeter of the bottom * Interface to SAS is not fixed at the moment.

16. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Structure of Radiation Shields Outer Shields Inner Shields Flame by A6000 Aluminum Secure stiffness of the radiation shields

17. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Modal analysis of outer shield M= Mode frequency M= S.Koike Remove support rod Mode Frequency

18. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Modal analysis of inner shield S.Koike M= Frequency

19. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Response to ground motion Jan. 31 st,2011 H. Yamaoka Input to peripheral of bottom Mozumi 50m K.Y. 2005

20. Cryo-top Cryo-L Cryo-F Input Cryo-R X-directionY-direction X 方向 Y 方向 Response to ground motion

21. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA MLI utilizes quite a lot of aluminized thin polyester films as radiation shields. The polyester film exhausts water vapor, which may dim the optical system of the Laser-Interferometer. The exhaust rate of the water vapor may be reduced much at cryogenic temperature. But it is important to know the general characteristics of out-gas rate at room temperature.

22. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA To reduce the total amount of out-gas, Thickness of polyester film must be thin Light Weight MLI Total number of films in MLI must be reduced High Thermal Resistance

23. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Specifications of Candidate MLI : KFP-9B08 ( provided by Tochigi Kaneka Co., Ltd.) *1 : estimated by the aluminum thickness data obtained by the atomic absorption spectroscopy reported by Teikyo University in the International Conference of Cryogenic Engineering, 2010 Type of MLI Double Aluminized Polyester Film Laminated with Separator MaterialAll Polyester Thickness Specific weight Surface Resistance of Vapor Deposited Aluminum Layer : Rs less than for each side of DAM Thickness of Aluminum Layer *1more than 50 nm for each side of DAM Normal Emissivity Less than 0.1 for non-laminated side Less than 0.6 for laminated side

24. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA Back ground (SUS Chamber) The measurement is now underway MLI : Kaneka KFP-9B08

25. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURA (2) High Thermal Resistance Heat transfer mechanisms in MLI q t = q r + q c Radiation term q r and Conduction term q c are comparable at good fabrication condition. Conduction term is governed by contact pressure between reflective films at the self-compression state. Radiation term is governed by total number of films. Thin polyester film will reduce the contact pressure from thermal resistance point of view. ⇒ Light weight MLI

26. GWADW2011 Elba/Italy, 26/May/2011 N. KIMURASummary 26 The design of the mirror cryostat for LCGT satisfying requirements was almost finished in one year. The production of the components for the cryostat will be started after contractor decided. Performance of the first cryostat will be demonstrated on the mid of 2012 Jfy. Proto type cryo-cooler units replaced with substituted materials will be completed on the end of this June. Performance of the first cryo-cooler will be confirmed on the mid of this July.