Operating Modes and Cooling Capabilities Operating Modes and Cooling - - PowerPoint PPT Presentation

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Operating Modes and Cooling Capabilities Operating Modes and Cooling - - PowerPoint PPT Presentation

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https://ntrs.nasa.gov/search.jsp?R=20150018884 2018-06-18T19:32:18+00:00Z National Aeronautics and Space Administration Operating Modes and Cooling Capabilities Operating Modes and Cooling Capabilities of the Flight ADR for the SXS Instrument

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SLIDE 1

National Aeronautics and Space Administration

NASA Goddard Space Flight Center

www.nasa.gov

Astro-H/SXS

Peter Shirron

Key ADR team members: Mark Kimball, Michael DiPirro

Operating Modes and Cooling Capabilities

  • f the Flight ADR for the SXS Instrument
  • n Astro-H

Operating Modes and Cooling Capabilities

  • f the Flight ADR for the SXS Instrument
  • n Astro-H

https://ntrs.nasa.gov/search.jsp?R=20150018884 2018-06-18T19:32:18+00:00Z

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SLIDE 2

Astro-H Soft X-ray Spectrometer Astro-H Soft X-ray Spectrometer

  • 6x6 array of x-ray microcalorimeters cooled to 50 mK

2

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SLIDE 3

ADR Driving Requirements ADR Driving Requirements

  • ADR is used to cool the detectors to 50 mK

– 0.25-0.40 µW of conducted heat (leads)

  • ADR rejects heat to either:

– Superfluid helium at <1.3 K

  • <0.23 mW average (4 year lifetime)

– Joule-Thomson cooler at ~4.5 K

  • <18 mW peak
  • Detector housing stable to 1 mK (time scales
  • f 02 sec to 10 min)
  • 90% observing efficiency

3

Requires 3-stage ADR

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SLIDE 4

2ST 2ST ADR Stage 2 ADR Stage 1 Dewar Main Shell, 300K Outer Vapor Cooled Shield, 155K Inner Vapor Cooled Shield, 28K JT Shield, 4.5K Detector Assembly, 1.3K 15K 4.5K HS 4 HS 2 HS 1 0.5K 0.05K HS 3 ADR Stage 3 Calorimeter Thermal Sink, 0.05K 2ST 2ST

4He JT

Astro-H Cryogenic System Astro-H Cryogenic System

LHe Tank 1.3K

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NASA/GSFC hardware

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SLIDE 5

ADR Layout ADR Layout

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3rd Stage 2nd Stage 1st Stage Mounting plate – mechanical and thermal I/F to He Tank Thermal strap To JT cooler

Astro-H/SXS FM CSI/HTS/ApA Pre-Ship Review March 27, 2014 NASA Goddard Space Flight Center

Heat switches

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SLIDE 6

2-Stage ADR 2-Stage ADR

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Astro-H/SXS FM CSI/HTS/ApA Pre-Ship Review March 27, 2014 NASA Goddard Space Flight Center

Stage 1:

  • 270 g CPA
  • 2 T, 2 amp

magnet Stage 2:

  • 150 g GLF
  • 3 T, 2 amp

magnet Heat switches are active gas-gap

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SLIDE 7

3rd Stage ADR 3rd Stage ADR

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Thermal strap to He tank

Astro-H/SXS FM CSI/HTS/ApA Pre-Ship Review March 27, 2014 NASA Goddard Space Flight Center

Thermal strap to JT

Stage 3:

  • 150 g GLF
  • 3 T, 2 amp

magnet

Heat switches are active gas-gap

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SLIDE 8

Flight ADR, Detector and Dewar (April ‘14) Flight ADR, Detector and Dewar (April ‘14)

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2ST 2ST ADR Stage 2 ADR Stage 1 Dewar Main Shell, 300K Outer Vapor Cooled Shield, 155K Inner Vapor Cooled Shield, 28K JT Shield, 4.5K Detector Assembly, 1.3K 15K 4.5K HS 4 HS 2 HS 1 0.5K 0.05K HS 3 ADR Stage 3 Calorimeter Thermal Sink, 0.05K 2ST 2ST

4He JT

Astro-H Cryogenic System Astro-H Cryogenic System

LHe Tank 1.3K

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SLIDE 10

2ST 2ST ADR Stage 2 ADR Stage 1 Dewar Main Shell, 300K Outer Vapor Cooled Shield, 155K Inner Vapor Cooled Shield, 28K JT Shield, 4.5K Detector Assembly, 1.3K 15K 4.5K HS 4 HS 2 HS 1 0.5K 0.05K HS 3 ADR Stage 3 Calorimeter Thermal Sink, 0.05K 2ST 2ST

4He JT

ADR Operation with Helium ADR Operation with Helium

LHe Tank 1.3K

  • 2-stage ADR operates by cascading heat

from the detectors to the liquid helium

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SLIDE 11

2ST 2ST LHe Tank EMPTY ADR Stage 2 ADR Stage 1 Dewar Main Shell, 300K Outer Vapor Cooled Shield, 155K Inner Vapor Cooled Shield, 28K JT Shield, 4.5K Detector Assembly, 1.3K 15K 4.5K HS 4 HS 2 HS 1 1.3K 0.05K HS 3 ADR Stage 3 Calorimeter Thermal Sink, 0.05K 1.3K 2ST 2ST

4He JT

Operation in Cryogen-Free Mode Operation in Cryogen-Free Mode

  • 3rd stage transfers heat to JT cooler
  • 2nd stage maintains helium tank temperature
  • 1st stage cools detectors to 50 mK

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Operation with Liquid Helium Operation with Liquid Helium

  • Recycling sequence

– Stage 1 and 2 are warmed to ~10% above the He bath

  • HS1 and HS2 turned ON

– Stages 1 and 2 charge to full field (2 T and 3 T)

  • HS2 is turned off

– Stage 2 cools Stage 1 (still at 2 T) to <0.8 K

  • HS1 is turned off

– Stage 1 is demagnetized to 50 mK, and Stage 2 to 0.5 K

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ADR Stage 2 ADR Stage 1 HS 2 HS 1 0.5K 0.05K Calorimeter Thermal Sink, 0.05K LHe Tank 1.3K

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SLIDE 13

50 mK Stage Operation 50 mK Stage Operation

  • 2-stage ADR is automatically recycled when the first stage

current falls below 5 mA

– Temperature control becomes less stable

1

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SLIDE 14

Stage 1 Performance Stage 1 Performance

  • Demagnetized from 0.75 K and 2 T (0.16 J max cooling capacity)
  • Hold time with He bath at 1.20 K is ~43 hours

– On orbit expect ~1.10 K and 38 hour hold time

  • Heat load is 0.87 µW

– Measured 84% heat absorption efficiency

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Heat loads to 50 mK

Heat switch: 0.015 µW Detector assy: 0.27 µW Kevlar susp: 0.58 µW

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SLIDE 15

2-Stage ADR Recycling 2-Stage ADR Recycling

  • Recycle time <1 hour, including recovery time

– Detector response stabilizes as detector and ADR components equilibrate

  • Control setpoints are based on the He tank temperature (uses mounting

plate T)

– Control system automatically adjusts to conditions during flight

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SLIDE 16

Temperature Stability Temperature Stability

  • Required stability: 2.5 µK rms
  • Actual: 0.37 µK rms

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0 .0 4 9 9 9 6 0 .0 4 9 9 9 7 0 .0 4 9 9 9 8 0 .0 4 9 9 9 9 0 .0 5 0 0 0 0 0 .0 5 0 0 0 1 0 .0 5 0 0 0 2 0 .0 5 0 0 0 3 0 .0 5 0 0 0 4 7 7 .2 7 .4 7 .6 7 .8 8 T (K) Elapsed time (hrs) Allowable range

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SLIDE 17

2-Stage ADR Operation Summary 2-Stage ADR Operation Summary

  • Recycle time, including detector equilibration: ~1 hour
  • Hold time:

43 hours

  • Instrument observing efficiency (duty cycle):

>97%

  • Temperature stability

<1 µK rms

  • Integrated heat flow to helium tank

– Hysteresis from S1 and S2 magnets 3.42 J – HS1/HS2 getter power 0.76 J – Heat from salt pills 7.84 J – Total 12.02 J

  • Time average load to He tank is 0.077 mW

– Requirement is <0.2 mW – If ADR is recycled every day, heat per cycle is ~10 J, avg is 0.115 mW

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SLIDE 18

2ST 2ST LHe Tank EMPTY ADR Stage 2 ADR Stage 1 Dewar Main Shell, 300K Outer Vapor Cooled Shield, 155K Inner Vapor Cooled Shield, 28K JT Shield, 4.5K Detector Assembly, 1.3K 15K 4.5K HS 4 HS 2 HS 1 1.3K 0.05K HS 3 ADR Stage 3 Calorimeter Thermal Sink, 0.05K 1.3K 2ST 2ST

4He JT

Cryogen-Free Operation Cryogen-Free Operation

  • 3rd stage transfers heat to JT cooler
  • 2nd stage maintains helium tank temperature (goal <1.5 K)
  • Builds up cooling capacity during hold time
  • 1st stage cools detectors to 50 mK, rejects heat to 2nd stage

18

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SLIDE 19

3rd Stage Cycling 3rd Stage Cycling

  • Cycle period ~21 minutes
  • Low temperature setpoint is continuously adjusted to match helium tank T
  • Time average heat lift of 2-3 mW in range of 1.4-1.8 K

– Helium tank parasitic load is ~0.6 mW – ADR internal heat generation is ~1.2 mW

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SLIDE 20

Full Cycle with He tank at 1.625 K Full Cycle with He tank at 1.625 K

  • S2 charges during S1

hold time

  • S1 is automatically

recycled when current falls below 20 mA

  • 40 minute recycle
  • 11.0 hour hold
  • >94% observing

efficiency

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SLIDE 21

He Tank Control He Tank Control

  • Lower He tank temperature = slower charging rate of Stage 2
  • On orbit, tank will be regulated at lowest temperature at

which Stage 2 charges completely during Stage 1 hold time

– 1.5-1.55 K, based on current test conditions – Will change if cryocooler performance degrades over time

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SLIDE 22

Stage 1 Cycling Stage 1 Cycling

  • Stage 1 automatically recycles at 10 mA current

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SLIDE 23

Detector Housing Temperature Stability Detector Housing Temperature Stability

  • Required stability is 1 mK over time scales of 0.2 s – 10 min

– Brief periods in which fluctuation is ~2 mK – With current detector performance, this is acceptable

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SLIDE 24

Heat Flow to the JT Cooler Heat Flow to the JT Cooler

  • Cycling was adjusted to give max heat flow of 30 mW

– Maximum flow tolerable at nominal input power

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SLIDE 25

Warm Start Warm Start

  • ADR must handle the case of a warm start

– He tank, ADR and detectors starting at 4.5 K – May be necessary after catastrophic warmup

  • Due to loss of cryocooler operation for long period
  • Due to issues with guard vacuum
  • Control must be autonomous

– No intervention via ground control

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SLIDE 26

Cooldown from 4.5 K Cooldown from 4.5 K

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SLIDE 27

Summary Summary

  • ADR operates successfully with 2 very different heat sinks
  • Demonstrated autonomous control in all operating modes

– 2-stage with helium – 3-stage in cryogen-free mode

  • Warm start, automatic recycling

– Pre-launch (maintain He temperature during launch hold)

  • Meets all instrument requirements

– Cooling power – Temperature stability – Instrument observing efficiency – Heat rejection to He bath or JT cryocooler

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