Cryocooler-Specific Application and Integration Example: The AIRS Instrument

Cryocooler-Specific Application and Integration Example: The AIRS Instrument
2015 CEC Cryocooler Short Course
Cryocoolers for Space Applications #4
R.G. Ross, Jr.
Jet Propulsion Laboratory
California Institute of Technology
Topics
June 2015
Space Cryocooler Historical Overview and
Applications
Space Cryogenic Cooling System Design and
Sizing
Space Cryocooler Performance and How It's
Measured
Cryocooler-Specific Application and Integration
Example: The AIRS Instrument
Copyright 2015 California Institute of Technology. Government sponsorship acknowledged. CL#15-2287
RGR 4-1RR-1
Session 4: Detailed Example
The AIRS Instrument
Topics
• Overview of AIRS Instrument
•
•
•
•
Example Application Ground Rules and Requirements
AIRS Cryosystem Conceptual Design
Cryosystem layout and cryo loads estimation
Important heatsinking considerations
• Sizing the Cryocooler for the Complete Mission Life Cycle
• BOL/EOL performance margin analysis
• Temperature Stability Requirements and Control
• Cryocooler Structural Integration Considerations
• Electrical Interface Considerations
• Meeting magnetic field requirements with shields
• Meeting Inrush and reflected ripple current requirements
June 2015
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References
June 2015
Ross, R.G., Jr. and Green K., "AIRS Cryocooler System
Design and Development," Cryocoolers 9, Plenum
Publishing Corp., New York, 1997, pp. 885-894.
Ross, R.G., Jr., Johnson, D.L., Collins, S.A., Green K. and
Wickman, H. “AIRS PFM Pulse Tube Cooler System-level
Performance,” Cryocoolers 10, Plenum, New York, 1999, pp.
119-128.
Ross, R.G., Jr., “AIRS Pulse Tube Cooler System Level
Performance and In-Space Performance Comparison,”
Cryocoolers 12, Kluwer Academic/Plenum Publishers, New
York, 2003, pp. 747-754.
Ross, R.G., Jr., “Cryocooler Load Increase due to External
Contamination of Low-¶Ý Cryogenic Surfaces,” Cryocoolers
12, Kluwer Academic/Plenum Publishers, New York , 2003,
pp. 727-736.
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References (Con't)
Ross, R.G., Jr. and Rodriguez, J.I., “Performance of the AIRS
Pulse Tube Coolers and Instrument—A first Year in Space,”
Adv. in Cryogenic Engin., Vol 49B, Amer. Inst. of Physics, New
York, 2004, pp. 1293-1300.
Ross, R.G., Jr., “Active Versus Standby Redundancy for
Improved Cryocooler Reliability in Space,” Cryocoolers 13,
Springer Science & Business Media, New York, 2005, pp. 609618.
Ross, R.G., Jr., et al., “AIRS Pulse Tube Coolers Performance
Update – Twelve Years in Space,” Cryocoolers 18, ICC Press,
Boulder, CO, 2014, pp. 87-95.
See the AIRS instrument web site for up-to-date descriptions
of the science returns from the AIRS instrument and its
science team members: http://www-airs.jpl.nasa.gov/
http://www2.jpl.nasa.gov/adv_tech/ JPL website with 103 JPL
cryocooler references as PDFs (R. Ross, webmaster)
June 2015
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AIRS (Atmospheric Infrared Sounder)
is a NASA Earth Science Instrument
• AIRS is an Atmospheric Infrared Sounder
• Design: Highly stable IR spectrometer
spanning visible to 15.4 ìm bands with
Focal Plane cooled to 58¶K
• Launched: May 2002
• Still in orbit gathering data
• Science Output:
• Air Temperature Distributions
• Atm Gas Concentrations
(CO, CO2, CH4, H2O) over Planet
Launched on NASA
Aqua Spacecraft in
May 2002
Water Vapor Transport
June 2015
RGR 4-5RR-5
Atmospheric Infrared Sounder
(AIRS) Instrument
AIRS
Instrument
HEAT REJECTION
COLD PLATES
190K
RADIATOR
150K
RADIATOR
The AIRS instrument was
designed and built under
JPL contract by BAE
Systems, Lexington, MA
AIRS Flight Instrument
OPTICAL
BENCH
EARTH SHIELD
June 2015
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AIRS Cryosystem Ground Rules
and Requirements
• Totally redundant cryocoolers—for enhanced reliability
• No heat switches—to avoid increased complexity, cost and
unreliability
• Ambient heat rejection to spacecraft-supplied cold plates
operating between 10 and 25oC
• Cooler drive fixed at 44.625 Hz, synchronized to the instrument
electronics
• Cold-end load (focalplane) mechanically mounted and aligned
to the 150 K optical bench with a maximum vibration jitter on
the order of 1 mm
• Focalplane calibration (for temperature, motion, etc.) every 2.67
sec (every Earth scan)
• Cooler input power goal of 100 watts (22 to 35 volts dc), and
mass goal of 35 kg
• Cooler drive electronics fully isolated (dc-dc) from input power
bus; EMI consistent with MIL STD 461.
June 2015
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Detector Technologies
and Temperatures
Radiation Wavelength Blackbody
(microns) Temp. (K)
Type
â-rays
â-rays
x-rays
x-rays
UV
visible
IR
IR
LWIR
LWIR
LWIR
LWIR
LWIR/ìwaves
microwaves
microwaves
June 2015
10-5
10-4
10-3
10-2
0.1
1
2
5
10
15
20
50
100
200
500
3 ´108 K
3 ´107 K
3 ´106 K
3 ´105 K
30,000 K
3000 K
1500 K
600 K
300 K
200 K
150 K
60 K
30 K
15 K
6K
Detector Detector Oper.
Temp. (K)
Technology
Ge Diodes
Ge Diodes
micro
calorimeters
CCD/CMOS
CCD/CMOS
HgCdTe
HgCdTe
HgCdTe
HgCdTe
Si:As
Ge:Ga
Ge:Ga
Bolometers
Bolometers
80 K
80 K
0.050 K
0.050 K
200-300 K
200-300 K
55-130 K
55-120 K
35-80 K
35-60 K
6 -10 K
2.0 K
1.5 K
0.100 K
0.100¶K
INTEGRAL
HST
AIRS
SIRTF
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Operating Regions of Cryocoolers
vs Detector Cooling Requirements
June 2015
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Candidate Stirling Cryocooler
Redundancy Approaches
AIRS
June 2015
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RR-10
AIRS Cryosystem Initial Conceptual
Design with Stirling Cryocoolers
Possible Issues
COLDFINGER
BUMPERS
June 2015
COUNTER
BALANCED
DISPLACER
• Displacer
heatsinking
• Displacer
vibration
• Displacer
reliability
RGR 4-11
RR-11
Hughes CSE Cryocooler Mounted
in Heat Sink Assemblies
June 2015
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Rapid Development of the Pulse
Tube Occurred Just in Time for AIRS
Specific Power at 58 K
Incorporation of
Inertance Tube
at TRW
(TRW Coolers)
1W-35K
June 2015
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AIRS Cryosystem Conceptual Design
with Pulse Tube Coolers
BOL: 145K
EOL: 160K
Possible Issues
• Optics
Contamination
• Pulse Tube
Contamination
• Horizontal PTs
• PT/OB relative
motion
June 2015
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Vacuum Level Considerations for
Space Cryogenic Applications
Three Vacuum Level Issues: Gaseous Conduction, Cryopumping
loads, Increased Emittance from contaminant films
Typical Vacuum Levels Achieved:
10-8 torr: Exterior to spacecraft sunlit surfaces (short term)
10-9 torr: Exterior to spacecraft sunlit surfaces (long term)
10-10 torr: Exterior to spacecraft shaded-side surfaces (long term)
Contamination Implications:
June 2015
Vacuum
Level
Time for
1 ìm H2O
H2O Cryopumping
Heat Transfer
10-6 torr
10-8 torr
10-9 torr
10-10 torr
1.7 hours
7 days
70 days
2 years
340 mW/m2
3.4 mW/m2
0.34 mW/m2
0.034 mW/m2
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AIRS Optical Bench
Contamination Risk Assessment
Optical Bench BOL Design: 145 K (10-8.5 torr): Contamination Likely
Optical Bench EOL Design: 160 K (10-6 torr): Looks Good
Pulse Tube Design: 55 K (10-50 torr): Contamination Very Likely
160K
145K •
Space •Vacuum
Pulse
Tubes
•
145K <10-8 torr
June 2015
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Massive Heat Sinks Added to
AIRS Pulse Tubes
June 2015
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Summary of AIRS Cooler System
Thermal Gradients
REGENERATOR
TEMPERATURE
ORIFICE
TEMPERATURE
•
•
•
COMPRESSOR
TEMPERATURE
COLDPLATE
TEMPERATURE
•
•
June 2015
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AIRS Cryosystem Cold Link Design
with Pulse Tube Coolers
June 2015
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AIRS Cold Link Assembly
Copper Flex Braid
Gold Plated
Sapphire Rod
June 2015
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Cryogenic Conductivity of
High Conductivity Materials
AIRS Cold Link
June 2015
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Breakdown of AIRS Coldlink
Assembly Thermal Resistances
ITEM
June 2015
Resistance
(K/W)
Focal plane to Sapphire rod
Conduction down Sapphire rod
1.57
0.16
Sapphire rod to moly coupling
Resistance across shrink-fit joint
0.34
0.40
Resistance across flex braid
Coldblock contact resistance
1.35
0.30
Total focal plane/pulse tube thermal resistance
4.12 K/W
RGR 4-22
RR-22
Summary of AIRS Instrument
Cryocooler Loads
FOCAL PLANE: 58 K, OPTICAL BENCH: 145 K BOL, 160 K EOL
ITEM
Focal Plane Radiation Load from OB
73
108
Focal Plane Electrical Dissipation
Focal plane Lead Wire Conduction
193
98
193
118
Focal plane Structural Support Conduction
Radiation to Coldlink from Optical Bench
129
17
158
24
Radiation to Coldlink from Vacuum Housing
Off-state Conduction of Redundant Cryocooler
177
486
195
496
1173
1292
Total Cryocooler Load
June 2015
Load (mW)
EOL
BOL
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AIRS Predicted Cryocooler
Thermal Performance
June 2015
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AIRS Cryocooler
Electronics Efficiency
June 2015
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AIRS BOL/EOL Performance
Margin Analysis
PARAMETER
Unit
K
Focalplane Temperature
W
Total Cooler Cold-End Load
K
Cooler Cold-tip DT to FP (3 K/W)
K
Cooler Cold-tip Temperature (TC)
K
Heat Rejection Coldplate Temp
K
Expander to Coldplate DT (0.16 K/W)
K
Comp. to Coldplate DT (0.05 K/W)
K
Avg. Cooler Rejection Temp (TR)
TC Correction for TR ¹ 300K (0.17 K/K)
K
K
TC Correction for Cooler Wearout
K
Total Cold-tip Temp Correction
K
Effective 300K Cold-tip Temp (TEC)
Cooler Specific Power at TEC
W/W
W
Cooler Compressor Power (P)
W
Total Input Power (P/0.9 + 10)
%
Compressor Stroke
June 2015
BOL
Performance
200 mW
Load
Increase
15oC
Heatsink
Increase
Cooler
Wearout
Degrad.
EOL
Performance
58
1.07
3
55
290
9.8
3.0
296
+0.7
0
+0.7
55.7
57
57
73
64
58
1.27
3.4
54.6
290
11.2
3.5
297
+0.5
0
+0.5
55.1
55
67
84
68
58
1.07
3
55
305
10.6
3.3
312
-2.0
0
-2.0
53.0
62
65
82
67
58
1.07
3
55
290
12.0
3.8
298
+0.3
-5.0
-4.7
50.3
72
75
93
70
58
1.27
3.4
54.6
305
16.8
5.3
316
-2.7
-5.0
-7.7
46.9
83
101
122
80
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AIRS BOL/EOL Operating State
Verification Analysis
EOL
BOL
1.07 1.27
June 2015
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Key Cryocooler Electrical
Integration Considerations
• Meet inrush and reflected ripple current requirements
June 2015
Accommodate broad input voltage ranges as compounded by
high ripple current of cooler
Suppress EMI to low levels consistent with MIL-Std 461 and
accommodate MIL-Std 461 susceptibility levels
Provide high isolation from ground loops: case isolated from
ground; possible dc-dc isolation from power bus
Provide digital data interface for communication of commands
and transmission of measured parameters & performance data
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AIRS Cryocooler Electronics
Conducted Ripple Current
Ripple
Filter
Cooler
Elect.
28V Bus
June 2015
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Prototype Magnetic Shields Used
in Magnetic Shielding Studies
June 2015
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AIRS Compressor AC Magnetic Fields
(With and Without Mag Shields)
AIRS coolers with
mag shields
June 2015
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AIRS Flight
Pulse Tube Coolers
Flight
AIRS
(NGAS)
TRW
Instrument
AIRS
PT Coolers
Launched on NASA
Aqua Spacecraft in
May 2002
June 2015
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Cooler Drive Level
During First 50 Days of Mission
June 2015
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Cooler Drive Level
During First 120 Days of Mission
June 2015
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Cooler Load Point
for 2-Cooler vs 1+Standby Operation
•
Operating Point
with one-cooler
operation
•
Operating Point
with two-cooler
operation
June 2015
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Cooler Drive Level Summary
for 12 Years of Operation
Cryocooler drive level has remained
relatively constant over past 12 years
June 2015
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AIRS Cooler Load Point
Since Two-Cooler Operation Began
•
Operating Point
with one-cooler
in operation
E
RIV
D
%
B
A
= BOL Operating Points with two-coolers in operation
= 12-year Operating Points with two-coolers in operation
June 2015
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Summary
• AIRS was the first space instrument to commit to a pulse tube
cryocooler and served as a very successful example
• Cooler performance characterization
• Dealing with Heat Rejection and Coldlink design
• Achieving tolerable generated vibration and EMI levels
• During the 20 years since the AIRS conceptual design was
developed, we've learned a great deal more about a number of
integration challenges:
•
•
•
•
•
Two-cooler operational redundancy trade-offs
Space vacuum levels and contamination sensitivity
Cryo MLI performance
Internal ripple current suppression
Lighter and more efficient 2-stage coolers that can accommodate
both the 150K optical bench load and the 58 K focal plane load
• Bottom Line: Space cryocoolers continue to evolve and we
continue to learn how to improve their system performance
June 2015
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