Cryogenic System design of LCGT Status of Cryogenic

Cryogenic System design of LCGT - Status of Cryogenic Design - N. KIMURAA, S. KOIKEB, T. KUMEB, T. OHMORID, Y. SAITOC, Y. SAKAKIBARAE, K. SASAKIA, Y. SATOC, T. SUZUKIA, T. UCHIYAMAE, K. YAMAMOTOE, H. YAMAOKAC, and LCGT Collaboration A Cryogenics Science Center/KEK B Mechanical Engineering Center/KEK C Accelerator Laboratory/KEK D Teikyo University E Institute for Cosmic Ray Research University of Tokyo/ICRR EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

ü ü ü Outline Required Issues for the Cryogenics Cryostat design • Components • Mechanical Analysis • Thermal Analysis • Performance of the proto-type cryocooler unit • Estimation cooling characteristics of the cryogenic load Schedule Future work Summary EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 2

Required Issues for the Cryogenics Design • Temperature of the test mass/mirror < 20 K. • Inner radiation shield have to be cooled < 8 K. • The mirror have to be cooled without introducing excess noise, especially vibration from the cryo-coolers. • Accessibility and enough space for the installation work around the mirror in the cryostat. Estimated by Dr. Uchiyama (ICRR) • Satisfy ultra high vacuum specification < 10 -7 Pa. EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

~3. 8 m Components of Mirror Cryostat to SAS Cryostat Stainless steel t 20 mm Diameter 2. 4 m Height ~3. 8 m M ~V 10 ton iew AS L n Mai Drawn by S. KOIKE (KEK) Remote valve por ts Low vibration cryocooler unit am e b ER Main beam (1200 mm FL) m 2. 4 Cryocoolers Pulse tube, 60 Hz 0. 9 W at 4 K (2 nd) 36 W at 50 K (1 st) Cryostat accompany with the four cryocooler units EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

The interior of the cryostat Drawn by S. KOIKE (KEK) Support rods View Ports Heat path to cryocooler EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA Double radiation shields with hinged doors

Static deformation analysis S. KOIKE Main vacuum duct and the duct to SAS are not connected. • periphery of the bottom : fix • EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

Modal analysis of outer shield Mode frequency Mass= Remove support rod Mode Frequency Mass= EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA S. KOIKE

Analyzing of Response to ground motion resonant frequency Cryo-top Cryo-F Cryo-L Cryo-R Y方向 X-direction X方向 Input Y-direction

Estimated Thermal Budget Estimated Heat Loads at the radiation shields and Support posts and rods 70 bythe thetop radiation 94 W K at of at the 80 80 K Koutershield 2. 27. 4 W Kbyatthe theradiation top of at the 8 K 8 inner shield K inner shield 2. 4 W by the radiation and conduction (support posts and Connection point with IM tension rods) at 8 K 24 W by the radiation and (support posts and 47 K atconduction 1 st cold stage tension rods) at 806. 5 K K at 2 nd cold of Cryo-cooler stage of Cryocooler d. T 1 st = 26 K Very High Purityd. T Aluminum 2 nd=0. 5 K Conductor (5 N 8) EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA Low Vibration Cryo-cooler unit 9

Estimated Heat load 1 st Cold stage • Outer Shield (W) ◦ Eleven View Ports 22 ◦ Radiation From 300 K 70 ◦ Support post and Rods 24 ◦ Electrical wires 3 x 10 -4 Total W/unit 116 29 2 nd Cold stage • 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 ? Total W/unit 5. 9 1. 5 *Heat Load of Duct Shields will be presented by Mr. Sakakibara. EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 10

Proto-type cryocooler unit under the performance test Pulse tube type cryo-cooler with anti-vibration stage Vacuum duct for very high pure aluminum thermal conductor and radiation shield EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA Tri-axial laser displacement meter

Vibration Level at edge of AL thermal conductor Axial Vertical Horizontal EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA PTC connection L=2 m

F. F. T. analysis (Ex. Axial direction) Results of displacement at connection point Axial < 200 nm Vertical < 50 nm Horizontal < 10 nm EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

Cooling curve of proto-type cryo-cooler unit Reached lowest temp. 2 nd stage=4. 8 K 1 st stage=37 K EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

Cooling Performance of Proto-type Cryo-cooler Unit Cooling Power per unit 4. 5 W at 8 K 48 W at 75 K EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

Estimation cooling characteristics Model is constructed to estimate initial cooling time Y. SAKAKIBARA Heat is transferred by conduction in sapphire fibers and heat links and radiation Inner shield of 410 kg is connected to the 2 nd stages of 4 cryocoolers ◦ Cooling power is derived from test result of proto-type cryo-cooler EGO-ICRR Meeting Suspension. Kashiwa, from isolation system 2011 is excluded Japan, 4 -5 October N. KIMURAin this case 16

Effect on Diamond Like Carbon coating Y. SAKAKIBARA Increased radiation by platform, intermediate mass, and inside of inner shield coated with DLC (Diamond Like Carbon) Absorptivity of DLC at 10 um is 0. 41 (cf. emissivity of Cu and Al is 0. 03) ◦ We assume that it equals emissivity EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 17

Production plan of LCGT mirror cryostats and peripheral components 2011 Jfy ‘ 11. 3 2012 Jfy ‘ 12. 3 ‘ 13. 3 We are here Four Mirror Cryostats Assemble and factory test with cryo-coolers ‘ 11. 09. 20&21 Contractors were decided; JEC- Tohrisya Toshiba Design by KEK Proto-type Cryo-cooler unit test ‘ 14. 3 Manufacture components Design by KEK Cryo-cooler units 2013 Jfy Production of 7 cryo-cooler units Custody at Kamioka Performance test Transport to Kamioka Performance test Duct shield units Design by KEK Transport to Kamioka Production of 9 cryo-cooler units Production of Proto-type ducts shield units with cryo-coolers EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA Custody at Kamioka

Mirror Cryostats with the duct shields Type-A (2 -layer structure) Vacuum duct 450 with radiation shield Mirror a cryostat Gate valve L=~17 m Vacuum duct 1000 with radiation shield EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA Upper tunnel containing pre-isolator (short IP and top filter) 1. 2 m diameter 5 m tall borehole containing standard filter chain Lower tunnel containing cryostat and payload Connection Port to SAS L=~17 m Vacuum duct 1000 with radiation shield Gate valve

Status of the cryogenic payload for LCGT • We have just started R&D and design work for the cryogenic payload based on the information from Roma. • Key person of the LCGT cryogenic payload group is Dr. K. Yamamoto. • Mr. Koike, mechanical engineer in KEK, is now calculating thermal analysis by ANSYS. • We are preparing a cryostat for the cryogenic payload at ICRR. • We would like to discuss it with INFN group during the workshop. 20

An example of a cryogenic payload’s drawing by S. KOIKE 21

A cryogenic payload in the cryostat Main L ASER beam drawing by S. KOIKE 22

Summary • • • The performance of the cryo-cooler unit with antivibration stage have almost confirmed, but need some modification to clear the specification. The design of the cryostat and cryo-cooler for LCGT were almost finished. The production of the components for the cryostat have just started in this September 2011. Performance of the first cryostat will be demonstrated on the mid of 2012 Jfy. Total performance of the first cryo-cooler will be confirmed on the mid of this August. To do works; We have to fix the design of two kinds of duct shields for beam duct and SAS connection. ² We also have to focus on R&D work for the cryogenic EGO-ICRR Meeting payload. ² Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 23

Back UP EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 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. EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

To reduce the total amount of out-gas, Thickness thin of polyester film must be Light Weight MLI Total number of films in MLI must be reduced High Thermal Resistance EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

Specifications of Candidate MLI : KFP-9 B 08 ( provided by Tochigi Kaneka Co. , Ltd. ) Type of MLI Double Aluminized Polyester Film Laminated with Separator Material All Polyester Thickness Specific weight Surface Resistance of Vapor Deposited Aluminum Layer : Rs less than 　　　for each side of DAM Thickness of Aluminum Layer *1 more 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 *1 : estimated by the aluminum thickness data obtained by the atomic absorption spectroscopy reported by Teikyo University in the International Conference of Cryogenic EGO-ICRR Meeting Engineering, 2010 Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

The measurement is now underway MLI : Kaneka KFP-9 B 08 Back ground (SUS Chamber) EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

(2) High Thermal Resistance Heat transfer mechanisms in MLI q t = qr + qc Radiation term qr and Conduction term qc 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 EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

F. F. T. analysis (Vertical direction) Vertical EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

F. F. T. analysis (Horizontal direction) Horizontal EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA

Appendix(Conduction cooling of suspension system, No radiation) Thermal conductivity of heat links or sapphire fibers limits cooling time EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 32

Appendix(Conduction and radiation cooling of suspension system) Radiation dominates above 100 K Conduction dominates below 100 K EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 33

Incident Thermal Radiation through Duct Shield and Cooling Time of Mirror Yusuke SAKAKIBARA (ICRR) 2011. 8. 4 EGO-ICRR LCGT f 2 f. Meeting meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 34

Incident Thermal Radiation through Duct Shield EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 35

Purpose of duct shield Thermal radiation from opening of 900 mm in diameter Cooling power 3. 6 W at 4 K (4 pulse tube cry coolers of 0. 9 W at 4 K) Thermal radiation can be decreased if solid angle reduces Thermal radiation reflected by metal shield pipe ◦ Problem experienced in CLIO Cryostat Duct Shield 900 mm EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 17 m 36

Reducing thermal radiation by baffles Incident thermal radiation calculated using ray trace model by counting up number of reflections (Aluminum of A 1070 measured at 10 um, 80 K) EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 37

Calculation of incident thermal radiation Apertures of baffles change linearly R=0. 94 at 10 um R=0. 94± 0. 02 Worse case R=0. 96 P=0. 172 W Better case R=0. 92 P=0. 0615 W EGO-ICRR Meeting Thermal radiation can be sufficiently Kashiwa, Japan, 4 -5 October 2011 N. KIMURA reduced by baffles 38

Cooling Time of Mirror EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 39

Summary • Thermal radiation through duct shield can be sufficiently reduced by baffles ◦ 200 m. W (100 m. W x 2 duct shields) It takes 20 days to cool down mirror with DLC coating ◦ Research for high emissivity coating is now underway EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 40

Calculation about incident heat through radiation shields of LCGT ducts ICRR，KEKA Yusuke Sakakibara，Nobuhiro Kimura. A， Toshikazu Suzuki. A，Kazuaki Kuroda， Yoshio Saito. A，Shigeaki Koike. A， Masatake Ohashi，Shinji Miyoki， LCGT Collaboration 2011. 9. 18　JPS 2011 Autumn Meeting EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 41

Contents Background ◦ Cooling mirror to reduce thermal radiation ◦ Cooling only cryostats ◦ Thermal radiation through holes of cryostat is problematic Calculating incident thermal radiation from ducts ◦ Comparison with experimental value Calculation in LCGT case S. KOIKE Vibration Isolation System Schematic diagram of cryostat Beam Duct Laser Beam Mirror(20 K) Inner Shield(8 K) Outer Shield(80 K) EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 42

Purpose of duct shield Thermal radiation from opening of 900 mm in diameter Cooling power 3. 6 W at 4 K (4 pulse tube cry-coolers of 0. 9 W at 4 K) It is necessary to reduce thermal radiation Thermal radiation appears to be proportional to solid angle to hole Solid Angle Cryostat Duct Shield 29. 2 W 900 mm EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 17 m 43

Cooling test in LCGT prototype（ CLIO） Thermal radiation reflected by duct shield ◦ Experimentally verified T. Tomaru et al. Jpn. J. Appl. Phys. 47 (2008) 1771 -1774 Incident power 　　Calculated by tracing rays (reflectivity is 0. 94) 600 times larger than considered from solid angle Solid Angle Cryostat Duct Shield 29. 2 W 900 mm EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 17 m 6. 22 W Although "black" duct shield absorbs thermal radiation, it radiates itself. 44

Reducing thermal radiation by baffles Reflecting thermal radiation to room temperature side by baffles Increasing number of reflections of rays by baffles Room Temperature Low Temperature EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 45

Calculation of incident thermal radiation It is necessary to reduce incident heat by optimizing layout and shape of baffles Incident thermal radiation calculated using ray trace model by counting up number of reflections : Area of baffle aperture : Number of reflections : Reflectivity of duct Subscript d means duct, r room temperature side of baffles , c cryogenic temperature side of baffles EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 46

Comparison with experimental value Experiment in prototype of cryogenic interferometer(CLIK) ◦ Tomaru T et al. J. Phys. : Conf. Ser. 122 (2008) 012009 ◦ Introducing 2 baffles, reflectivity of duct and baffles is 0. 95 ◦ Incident heat 7. 9 m. W Calculated value 18. 6 m. W Calculated value is consistent with experimental value within several times ◦ If reflectivity is 0. 90, calculated value is exactly experimental value ◦ Change of several percent of reflectivity leads to several times’ difference of incident heat because of many reflections. 3 cm 117 cm Room Temperature 7 cm Cryogenic Temperature Baffle EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 2. 3 cm 135 cm 47

Calculation in LCGT case Apertures of baffles change linearly R=0. 94 at 10 μm (reflectivity of duct and baffles) EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA R=0. 94± 0. 02 (measured value of aluminum A 1070 at wavelength 10 μm, 80 K) Worse case R=0. 96 P=0. 283 W Better case 48 R=0. 92 P=0. 100 W

High absorptivity coating （DLC） Room Temperature Cryogenic Temperature DLC coating Position of baffles x=0, 14, 16, 17 m Without DLC 0. 163 W With DLC 0. 0883 W Heat absorbed by baffles Heat load becomes smaller Baffles whose room temperature sides are coated with DLC (Diamond-Like -Carbon) Baffles whose cryogenic temperature sides are NOT coated with DLC because it radiates • Reflectivity of Aluminum A 1070　CP+DLC(1. 0 μm in thickness) at wavelength 10 μm, 80 K is measured; 0. 59 ◦ Reflectivity of duct 0. 94 ◦ Reflectivity of room temperature sides of baffles 0. 59 EGO-ICRR Meeting ◦ Reflectivity of cryogenic temperature sides of baffles 0. 94 Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 49

Budget of thermal loads on 2 nd stages of LCGT cryocoolers Heat sources ◦ Radiation through duct shields ◦ Eleven view ports ◦ Radiation from outer shield ◦ Conduction from supports ◦ Absorption of laser by mirror ◦ Scattering of laser by mirror Total W 0. 3 0. 4 2. 2 2. 4 0. 9 N. KIMURA ～ 3 ～ 9 Thermal radiation through duct shields can be sufficiently reduced by baffles EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA S. KOIKE 50

Summary ◦ We calculated incident thermal radiation through duct shield ◦ Calculated value is consistent with experimental value ◦ Thermal radiation can be sufficiently reduced by baffles ◦ Baffles coated with high absorptivity coating were useful Future works ◦ We will calculate detail to design LCGT duct shields ◦ We will verify calculation result using LCGT cryostat EGO-ICRR Meeting Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 51

Appendix (Heat capacity) Sapphire: Y. S. Touloukian: "Thermophysical Properties of Matter Volume 5 Specific Heat Nonmetallic Solids, " IFI/Plenum (1970) Copper: EGO-ICRR AIST Network Database System for Thermophysical Property Data Meeting Aluminum: NIST http: //cryogenics. nist. gov/MProps. MAY/5083%20 Aluminum/5083 Aluminum_rev. htm Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 52

Appendix (Thermal conductivity) Sapphire: Y. S. Touloukian: "Thermophysical Properties of Matter Volume 5 Specific Heat Nonmetallic Solids, " IFI/Plenum (1970) EGO-ICRR Meeting Aluminum: AIST Network Database System for Thermophysical Property Data Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 53

Appendix (Emissivity) Sapphire: Y. S. Touloukian: "Thermophysical Properties of Matter Volume 5 Specific Heat Nonmetallic Solids, " IFI/Plenum (1970) Copper: EGO-ICRR Y. Sakakibara. Meeting et al. TEION KOGAKU 2011; 46 Kashiwa, Japan, 4 -5 October 2011 N. KIMURA 54

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