1 / 55

Cryogenic System design of LCGT - Status of Cryogenic Design -

Cryogenic System design of LCGT - Status of Cryogenic Design -. N. KIMURA A , S. KOIKE B , T. KUME B , T. OHMORI D , Y. SAITO C , Y. SAKAKIBARA E , K. SASAKI A , Y. SATO C , T. SUZUKI A , T. UCHIYAMA E , K. YAMAMOTO E , H. YAMAOKA C , and LCGT Collaboration. A Cryogenics Science Center/KEK

keenan
Download Presentation

Cryogenic System design of LCGT - Status of Cryogenic Design -

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 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

  2. Outline • Required Issues for the Cryogenics • Cryostat design • Components • Mechanical Analysis • Thermal Analysis • Performance of the proto-type cryo-cooler unit • Estimation cooling characteristics of the cryogenic load • Schedule • Future work • Summary

  3. 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. • Satisfy ultra high vacuum specification • < 10-7 Pa. Estimated by Dr. Uchiyama (ICRR)

  4. Components of Mirror Cryostat Cryostat accompany with the four cryocooler units to SAS Cryostat Stainless steel t20mm Diameter 2.4m Height ~3.8m M ~ 10 ton Drawn by S. KOIKE (KEK) Remote valve View ports ~3.8m Low vibration cryocooler unit Main LASER beam Cryocoolers Pulse tube, 60Hz 0.9 W at 4K (2nd) 36 W at 50K (1st) Main beam (1200mm FL) 2.4m

  5. The interior of the cryostat Drawn by S. KOIKE (KEK) Support rods Double radiation shields with hinged doors View Ports Heat path to cryocooler

  6. Static deformation analysis • Main vacuum duct and the duct to SAS are not connected. • periphery of the bottom : fix S.KOIKE

  7. Modal analysis of outer shield S.KOIKE Mode frequency Mass= Remove support rod Mode Frequency Mass=

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

  9. Estimated Thermal Budget Estimated Heat Loads at the radiation shields and Support posts and rods 94 K at the top of the 80 K outer shield 70 W by the radiation at 80 K outer shield 2.2 W by the radiation at 8 K inner shield 7.4 K at the top of the 8 K inner shield 2.4 W by the radiation and conduction (support posts and tension rods) at 8 K Connection point with IM 24 W by the radiation and conduction (support posts and tension rods) at 80 K 47 K at 1st cold stage of Cryo-cooler 6.5 K at 2nd cold stage of Cryo-cooler dT1st = 26 K Very High Purity Aluminum Conductor (5N8) dT2nd=0.5 K Low Vibration Cryo-cooler unit

  10. Estimated Heat load 1st Cold stage 2nd 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 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 ? • Total 5.9 • W/unit 1.5 *Heat Load of Duct Shields will be presented by Mr. Sakakibara.

  11. 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 Tri-axial laser displacement meter

  12. Vibration Level at edge of AL thermal conductor Vertical PTC connection Axial L=2 m Horizontal

  13. F.F.T. analysis (Ex. Axial direction) Results of displacement at connection point Axial < 200 nm Vertical < 50 nm Horizontal < 10 nm Axial

  14. Cooling curve of proto-type cryo-cooler unit Reached lowest temp. 2nd stage=4.8 K 1st stage=37 K

  15. Cooling Performance of Proto-type Cryo-cooler Unit Cooling Power per unit 4.5 W at 8 K 48 W at 75 K

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

  17. 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

  18. Production plan of LCGT mirror cryostats and peripheral components 2011 Jfy 2012 Jfy 2013 Jfy ‘11.3 ‘12.3 ‘13.3 ‘14.3 We are here Four Mirror Cryostats Manufacture components Transport to Kamioka Design by KEK Assemble and factory test with cryo-coolers ‘11.09.20&21 Contractors were decided; JEC- Tohrisya Toshiba Custody at Kamioka Cryo-cooler units Performance test Design by KEK Transport to Kamioka Production of 7 cryo-cooler units Performance test Proto-type Cryo-cooler unit test Custody at Kamioka Production of 9 cryo-cooler units Duct shield units Production of Proto-type ducts shield units with cryo-coolers Design by KEK

  19. Mirror Cryostats with the duct shields Type-A (2-layer structure) Vacuum duct450 with radiation shield Connection Port to SAS Mirror a cryostat Gate valve Gate valve L=~17 m L=~17 m Vacuum duct1000 with radiation shield Vacuum duct1000 with radiation shield Upper tunnel containing pre-isolator(short IP and top filter) 1.2m diameter 5m tall borehole containing standard filter chain Lower tunnel containing cryostat and payload

  20. 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.

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

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

  23. Summary • The performance of the cryo-cooler unit with anti-vibration 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. • We also have to focus on R&D work for the cryogenic payload.

  24. Back UP

  25. 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.

  26. 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

  27. 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

  28. The measurement is now underway MLI : Kaneka KFP-9B08 Back ground (SUS Chamber)

  29. (2) High Thermal Resistance • Heat transfer mechanisms in MLI qt = 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

  30. F.F.T. analysis (Vertical direction) Vertical

  31. F.F.T. analysis (Horizontal direction) Horizontal

  32. Appendix(Conduction cooling ofsuspension system, No radiation) • Thermal conductivity of heat links or sapphire fibers limits cooling time

  33. Appendix(Conduction and radiation cooling of suspension system) Radiation Radiation dominates above 100 K Conduction dominates below 100 K

  34. Incident Thermal Radiation through Duct ShieldandCooling Time of Mirror Yusuke SAKAKIBARA (ICRR) 2011.8.4 LCGT f2f meeting

  35. Incident Thermal Radiation through Duct Shield

  36. 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 Cryostat Duct Shield 900 mm 17 m

  37. Reducing thermal radiation by baffles • Incident thermal radiation calculated using ray trace model by counting up number of reflections (Aluminum of A1070 measured at 10 um, 80 K)

  38. 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 • Thermal radiation can be sufficiently reduced by baffles

  39. Cooling Time of Mirror

  40. Summary • Thermal radiation through duct shield can be sufficiently reduced by baffles • 200 mW (100 mW x 2 duct shields) • It takes 20 days to cool down mirror with DLC coating • Research for high emissivity coating is now underway

  41. Calculation about incident heat through radiation shields of LCGT ducts Yusuke Sakakibara，Nobuhiro KimuraA， Toshikazu SuzukiA，Kazuaki Kuroda， Yoshio SaitoA，Shigeaki KoikeA， Masatake Ohashi，Shinji Miyoki， LCGT Collaboration ICRR，KEKA 2011.9.18JPS 2011 Autumn Meeting

  42. 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)

  43. 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 Cryostat Duct Shield 29.2 W 900 mm 17 m

  44. 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 Cryostat Duct Shield 29.2 W 6.22 W • Although "black" duct shield absorbs thermal radiation, it radiates itself. 900 mm 17 m

  45. 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

  46. 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

  47. 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 mW • Calculated value 18.6 mW • 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 Cryogenic Temperature Baffle 7 cm 2.3 cm 135 cm

  48. Calculation in LCGT case • Apertures of baffles change linearly R=0.94±0.02 (measured value of aluminum A1070 at wavelength 10 μm, 80 K) Worse case R=0.96 P=0.283 W Better case R=0.92 P=0.100 W R=0.94 at 10 μm (reflectivity of duct and baffles)

  49. High absorptivity coating （DLC） Room Temperature Cryogenic Temperature • 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 A1070CP+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 • Reflectivity of cryogenic temperature sides of baffles 0.94 DLC coating Position of baffles x=0,10,14,16,17m Without DLC 0.163 W With DLC 0.0883 W Heat absorbed by baffles Heat load becomes smaller

  50. Budget of thermal loads on 2nd stages of LCGT cryocoolers • Heat sources W • Radiation through duct shields 0.3 • Eleven view ports 0.4 • Radiation from outer shield 2.2 • Conduction from supports 2.4 • Absorption of laser by mirror 0.9 • Scattering of laser by mirror ～3 • Total ～9 N. KIMURA • Thermal radiation through duct shields • can be sufficiently reduced by baffles S. KOIKE

More Related