Upload
josephine-smith
View
221
Download
1
Tags:
Embed Size (px)
Citation preview
Development of Low Vibration Cryocooler
KEK Tomiyoshi Haruyama
1. Cooling requirements2. GM/Pulse Cryocooler3. Vibration measurement4. R&D of low vibration cryocooler
2003.2.6-7 TAMA Symposium, ICRR, Kashiwa
Cooling Requirements-Cryostat concept
4K Pulse tube Cryocooler
K4
Compressor
RT suspension
10K
20K
80K Pulse tube Cryocooler
Heat link
80K shield5m
Mirror
Buffer mass
4K shield
Cooling requirement
COOLING POWER-Mirror cooling
0.5W at 4.2K20W at 40K
-5m Shield cooling50W at 80K
VIBRATION at COLDENDS
-<10-7 m at 1Hz
CRYOCOOLER
Advantages-Easy to operate-Maintenance free (for 1-2 years)-No danger in tunnel (no cryogen)
Disadvantages-Sound + vibration
→Origin?
Driving mechanism
GM Cryocooler Pulse Tube Cryocooler
Compressor CompressorRegenerator Regenerator
CompressorPulse tube
Rotary valveRotary valve
Displacer
Motor
Origin and level of vibration
Solid piston
Driving motor
Pressure wave
GM~ ~ ~ ~
~Severe
~ ~ ~Intrinsic
Pulse tube Quiet
~ ~ ~Intrinsic
Commercially available 4K cryocooler
GM-Sumitomo Pulse-Cryomech Pulse-Sumitomo
Driving motor Buffer tank only
Vibration measurement at low temperature
CryocoolerAccelerometer
Reflector
Opt sensor
Sustaining post
Cryostat
Reflection displacement sensor
Cryomech and Sumitomo 4K PT cryocooler
Pulse-Cryomech Pulse-Sumitomo
Driving motor+buffer tank
Buffer tank only(separated motor)
Final problem?-Pressure wave
x=pRL
6kt
k: bulk modulus E/3(1-2 )
Example:SUSφ40X200,t=1Δp = 2MPaΔx = ~8μm( Experiment : 6~30μm )
圧縮機
L
2R
t
Soft thermal link at cold stage
25μm→ < 3μm @ RT 1HzSingle stage, 77 K6μm→0.5μm
CRYOMECH Giessen Univ.
Concluding Remarks
-Pulse tube cryocooler: Final solution for mirror cooling
-Thermal link (vibration free stage):Key technology (R&D is going on)
-Innovative idea for vibration-free cold end: Prepare for testing
Concluding Remarks-Schedule
-April 2003 R&D cryocoolers will be dispatched-July 2003 Vibration/Cooling performance test-September 2003 Production will be started-March 2004 All the coolers will be available