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Cryogenics for FPPS. Masi
• Two inter-related issues:
– Cryogenic chain for the focal plane (final temperature 0.1K)
– Thermal system to radiatively cool the telescope (final Temperature as low as possible, hopefully 30K)
Planck JT cooler
20K -> 4.5K
P.S. 70W @ 300K
Load 300 mW @ 20KHeat lift 14mW @4.5K
Grenoble dilution (open cycle)
Possible Dry Cryogenic Chain for FPP focal plane (Replicate Planck, 2 years lifetime)
4.5K -> 0.1K
P.S. -
Load 2 mW @ 4.5KHeat lift 0.1uW @0.1K
FLOWN FLOWN
FLOWN
(10M€)(16M€)
RAL
(??M€)
Radiative cooling to <50KWith V-grooves
FLOWN
Sorption Cooler
http://www.dta.airliquide.com/en/our-offer/space/equipments/cryo-refroidisseurs-tube-a-gaz-pulse-10-k-80-k.html
300K -> 20K
P.S. 200W @ 300K
Heat lift 5W @ 80KHeat lift 300mW @20K
Planck JT cooler
20K -> 4.5K
P.S. 70W @ 300K
Load 300 mW @ 20KHeat lift 14mW @4.5K
Grenoble dilution (open cycle)
Air-Liquide + CEA/SBT + Thales Cryogenics BV
Possible Dry Cryogenic Chain for FPP focal plane (2 years)Partial replication of Planck, but simpler 20K system
4.5K -> 0.1K
P.S. -
Load 2 mW @ 4.5KHeat lift 0.1uW @0.1K
FLOWN FLOWNSPACE QUALIFIED (10M€)(16M€)
RAL
(??M€)
PULSE TUBE
http://www.dta.airliquide.com/en/our-offer/space/equipments/cryo-refroidisseurs-tube-a-gaz-pulse-10-k-80-k.html
300K -> 20K
P.S. 200W @ 300K
Heat lift 5W @ 80KHeat lift 300mW @20K
Planck JT cooler
20K -> 4.5K
P.S. 70W @ 300K
Load 300 mW @ 20KHeat lift 14mW out @1.6K
Continuous ADR 4 stage(NASA-GSFC)8 kg
Air-Liquide + CEA/SBT + Thales Cryogenics BV
Alternative Dry Cryogenic Chain for FPP focal plane (>4 years)
6K -> 0.1K
P.S. -
Load 35 mW @ 4.5KHeat lift 30 uW @0.1K
RAL
TRL2-3
FLOWNSPACE QUALIFIED (16M€)(??M€)
(??M€)
PULSE TUBE
http://www.dta.airliquide.com/en/our-offer/space/equipments/cryo-refroidisseurs-tube-a-gaz-pulse-10-k-80-k.html
300K -> 20K
P.S. 200W @ 300K
Heat lift 5W @ 80KHeat lift 300mW @20K
Planck JT cooler
Continuous Dilution(Grenoble)
Air-Liquide + CEA/SBT + Thales Cryogenics BV
Alternative Dry Cryogenic Chain for FPP focal plane (>4 years)
1.6K -> 0.1K
P.S. -
Load ? mW @ 1.6KHeat lift 1uW @0.05K
SPACE QUALIFIED
FLOWN
RAL
Lab Tests done: TRL2-3
20K -> 4.5K
Sorption or JT Cooler4.5K -> 1.6K
FLOWN, to be modified
PULSE TUBE
Radiative cooling of telescope• Would the telescope be thermally
disconnected from the spacecraft, it would cool down radiatively:
• A mass of 400 Kg of Al with a 3m2 surface blackbody radiating to cold space would get to 4 K in 44 days (more or less the cruise to L2).
• The key is then to limit the heat transfer from the spacecraft and from the sun, earth, etc.
• Planck did it very well using V.grooves to limit radiation, low conductivity struts and pipes.
• We might be able to do better with FPP: – Little power dissipation from detectors– Lower number of pipes / Waveguides– Use of Passive Orbital Disconnecting
Struts (PODS)– Use of part of the 20K pulse tube
cooling power (or a second, dedicated one)
Spacecraft 300K
Telescope 30K or less
Radiative heat transfer
Conductive heat transfer
Spitzer: Gamma-alumina/epoxy composite struts (yellow) : Better than fiberglass (COBE) and Titanium struts.
or gamma-alumina
Mass Budget
• TBD
Heat Load Budget• On the 0.1K stage:
– Superconduncting wiring for 200 (?) SQUIDs multiplexing 2000 detectors, + first stage SQUIDs dissipation (2 W)
– Supports for focal plane assembly (cold plate, horns, filters)
• On the 4K stage:– Wiring for readout electronics– Support system to 20K stage– Load from 0.1K cooler
• On the 20K stage– Load from support system to 30-40K radiatively cooled stage – Load from 4K cooler (300 mW)
• On the 40K stage– Load from support system to 300K stage– Residual radiative load through V.grooves– Load from 20K cooler (partial)