present design of lcgt cryogenic payload - status of cryogenic design -
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GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Present Design of Present Design of LCGT Cryogenic PayloadLCGT Cryogenic Payload- Status of Cryogenic Design -- Status of Cryogenic Design -
N. KIMURA*, Y. SAKAKIBARA**,
S. KOIKE*, T. OHMORI***, T. SUZUKI*,
H. YAMAOKA*, and LCGT Collaboration
* High Energy Accelerator Research Organization (KEK)
** University of Tokyo
*** Teikyo University
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA2
Outline
• Design of the LCGT cryogenics Structure of the cryostat
Cryostat response to ground motion
at CLIO/Kamioka mine
Thermal Budget of the cryostat
Estimation of heat load of the Mirror
from the beam duct shields
(by Mr. SAKAKIBARA)
• Summary
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Vacuum duct800 with radiation shield
Gate valve Gate valve
Connection Port to SAS
Mirror a cryostat
Location of Four Mirror Cryostats with the Cryo-coolersfor the LCGT
Mozumi-End
Atotsu-End
X-Front RoomY-Front Room
Vacuum duct800 with radiation shield
L=~20 m
L=~20 m
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Production plan of LCGT mirror cryostats Production plan of LCGT mirror cryostats and peripheral componentsand peripheral components
Manufacture components
Assemble and factory test with cryo-coolers
Transport to Kamioka
Custody at Kamioka
2011 Jfy 2012 Jfy 2013 Jfy
‘12.3 ‘13.3 ‘14.3‘11.3
Design by KEK
Bidding
We are here
Four Mirror Cryostats
Cryo-cooler units
Design by KEK 1st Prot-type Cryo-cooler unit test
Production of seven cryo-cooler units
Production of nine cryo-cooler units
Transport to Kamioka
Custody at KamiokaPerformance test
Duct shield units
Design by KEK Production of Prot-type ducts shield units with cryo-coolers
Performance test
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Basic requirements from LCGT Basic requirements from LCGT cryogeniccryogenic
• Temperature of the test mass/mirror : 20 [K]
Inner radiation shield have to be cooled to < 8 K
• The mirror have to be cooled without introducing
excess noise, especially vibration due to cryocoolers.
• Easy access and enough capacity
to installation work around the mirror.
• Satisfy ultra high vacuum specification < 10-7 Pa
Requirements and Answers
Answer to the requirements
• Adopt Pulse Tube-type Cryo-cooler units with very low vibration mount
based on the CLIO type cooler. • Adopt 2200 of inner diameter of flanges
for installation work of the mirror and suspension.• Analysed the cryostat response to
ground motion at Kamioka-mine.• Heat load from components as low as possible.• Develop very low out gas super insulation system for radiation heat load for ultra high vacuum
specification < 10-7 Pa
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Main beam(1200mm FL)
to SAS
View ports
Remote valve
Low vibration cryocooler unit
Main LASER beam
2.4m
~3
.8m
CryostatStainless steel t20mmDiameter 2.4mHeight ~3.8mM ~ 10 ton
CryocoolersPulse tube, 60Hz0.9 W at 4K (2nd)36 W at 50K (1st)
Drawn by S. Koike (KEK)
Cryostat accompany with four cryocooler Cryostat accompany with four cryocooler unitsunits
Structure of Mirror Cryostat
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
The interior of the cryostat The interior of the cryostat
Double radiation shields with hinged doors
Support rods
View Ports
Heat path to cryocooler
Drawn by S. Koike (KEK)
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Structure of Structure of Radiation Radiation ShieldsShields
Outer ShieldsOuter Shields Inner ShieldsInner Shields
Flame made by Flame made by A6000A6000AluminumAluminum
Secure stiffness and conductivitySecure stiffness and conductivityof the radiation shieldsof the radiation shields
Cryo-top
Cryo-L
Cryo-F
Input
Cryo-R
X-direction Y-directionX方向
Y方向
Response to ground motion
resonant frequency
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA10
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 116W/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 5.9W/unit 1.5
*Heat Load of Duct Shields will be told by Mr. Sakakibara
1st Cold stage
2nd Cold stage
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA11
Estimated Thermal BudgetEstimated 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)
Connection point with IM
dT2nd=0.5 K
94 K at the top of the 80 K outer shield
7.4 K at the top of the 8 K inner shield
47 K at 1st cold stage of Cryo-cooler 6.5 K at 2nd cold
stage of Cryo-cooler
dT1st = 26 K
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA12
Outline
• Concept of the LCGT cryogenics Structure and Response to
ground motion at CLIO/Kamioka mine
Thermal Budget of the cryostat
Estimation of heat load of the Mirror
from the beam duct shields
(by Mr. SAKAKIBARA)
• Summary
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Thermal radiation from opening of 500 mm in diameter
Cooling power 3.6 W at 4 K
(inner shield, 4 pulse tube cryo-coolers of 0.9 W at 4 K) Thermal radiation appears to be reduced by reducing solid
angle
13
Estimation of heat load from the beam duct shields of the Mirror in the Cryostat
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Problem experienced in CLIOProblem experienced in CLIOThermal radiation reflected by metal shield pipe Incident power
(calculated using ray trace model,experimentally verified by T. Tomaru, et al. 2008 )
Very large compared with solid angle
14animation
300 K 4 K
mirror
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Reducing heat load by bafflesReducing heat load by baffles
Incident power calculated using ray trace model by counting up number of reflections
15
animation
(Aluminum of A1070 measured at 10 m, 100 K)
300 K 4 K
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Result of calculationResult of calculation
16
16
R=0.94±0.02Worse caseR=0.96 P=52.4 mWBetter caseR=0.92 P=17.6 mW
R=0.94
300 K 4 K
mirror
• The better result for the case that intervals of baffles are not equal to each other– If intervals of baffles are equal, ray whose angle
passes through one baffle also passesthe other baffles
x=20 mx=0 m
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
DDiamond iamond LLike ike CCarbon coatingarbon coating
Baffles whose room temperature sides are coated with DLC Assuming reflectivity 0.35 (measured at 1 m
at room temperature by T. Tomaru, et al. 2005) Preparation for measurement at 10 m, cryogenic
temperature
is now underway
17
DLC coating
Heat absorbed by bafflesHeat load becomes smaller
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Summary 1Summary 1
18
• Sum of heat load from openings of cryostat can be sufficiently reduced by baffles
◦ 37 mW (18.4 mW x2)◦ Problem in CLIO solvedOne prototype duct shield will be constructed
until the end of March, 2013. The duct shield will be tested to verify this
calculation with the mirror cryostat.
GWADW2011 Elba/Italy, 23/May/2011 N. KIMURA and Y. SAKAKIBARA
Summary 2Summary 2
19
The design of the mirror cryostat for LCGT satisfying requirements was almost finished.
The production of the components for the cryostat will be started after decided contractor.
Performance of the first cryostat will be demonstrated at the factory of the contractoron the mid of 2012 Jfy.
We would like to discuss the detailed design process of the cryostat with participants of GWADW conference after this talk.
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