ESA Document - Emits - ESA

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HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 181 of 422
Note that, in Europe two ESA activities (Air liquid/Thales and Astrium/RAL TRP) are running
for this technology with performance ranging from 800mW (required) to 7W at 80K.
Development is oriented to detector cooling, but other applications requiring equivalent heat lift
at higher temperature (up to 120K) do not present any showstoppers (performance is increased).
Dewar design
Following previous figures, two tanks of diameter 0.75 m and pressurised to 10 bars are selected.
Each tank consists of a primary aluminum shell 3.5 mm thick, completed by a second shell
enclosing the MLI stack (vacuum between the two shells). An external goldenized kapton foil
insulates radiatively the external shell.
compressor
outer shell + goldenized kapton
pulse tube
cold finger
LOX
MLI, vacuum
Figure 3-41: TES (L) and IMAS (R) pulse tubes (L), Cryostat and coolers schematic (R)
Two coolers are mounted on each pole of the tank, the cold finger connected to the internal shell
via a thermal ‘doubler’ to better the thermal contact. To reduce parasitic thermal loads, Orbital
Disconnect Struts (ODS) are used. Location of ODS and tubing are chosen close to the pulse
tubes to reduce their thermal impacts.
3.3.3.6 Budget
Synthesis per subsystem (main features)
Fluid loops
Primary loop Pump assembly: 67 kg, 463W nominal (950kg/hr) (x 2)
Condenser heat exchangers: 20.6 kg (x 2),cold plates: 3.4kg (x
10), valves (on/off, manual): 4kg (x 20)
120 kg of tubing (dry including insulation, brackets) + 105kg of
water
4 coils mounted on the main body (38 m of heat pipes to spread
energy): total 79 kg (including fluid)
Secondary loop Pump assembly: 56.7 kg, 311W nominal (x 2)
Heat exchangers: 15.9 kg (x 4), cold plates: 3.4kg (x 5), valves
(on/off, manual): 4kg (x 5)
36 kg of tubing (dry including insulation, brackets) + 31kg of
ammonia