1. Thermal Control of IR detector
Roger Haroutunian (IPNL,Lyon)
CNRS (IN2P3,INSU) FRANCE

2. Specifications of elements
Main specifications of thermal elements
Temperature changes < 1 °/mn
Range of variation from 90K to 140K
Stability
November 15 & 16, 2005
Roger Haroutunian

3. Overall view COLD PLATE TROUGHPUT SPACERS (for strips) THERMAL SCREEN
November 15 & 16, 2005
Roger Haroutunian

4. Thermal control Thermal damping November 15 & 16, 2005
Roger Haroutunian

5. Thermal control Heat Sources/Sinks Neglected
Damping fiberglass supports
Copper strips/connecting Kapton (100 lines (15µm x 120µm) :
- From Moly support to thermal screen (5cm)
- From Thermal screen to (15cm)
Black body radiation vessel screen + cold plate 9.2W
Neglected
N2 Transfer lines
Cold finger for detector protection against dust
Kapton conduction
Detector and electronic
November 15 & 16, 2005
Roger Haroutunian

6. Thermal control Uncertainties
Quality of thermal connection at interfaces
Evolution of conductivity and capacity as a function of temperature
( Litterature may be off. )
November 15 & 16, 2005
Roger Haroutunian

7. Schematic layout Al Cold plate (77K ) 3 Fiberglass supports
Copper strips
Al Cold plate
Al Cold Plate
Cooling spacers
Thermal damping
Moly support
Thermal screen
(77K )
Pressure vessel
November 15 & 16, 2005
Roger Haroutunian

8. Input power (Impact/Moly support) Watts Effect DT (Moly) T=140K
Radiation
9.2W
N2 consumption
Support conduction
<1.4W
Strips/
Connections
T(Mo)
-0.065
+0.006
Vacuum
(10-5 Torr)
~0.0001
November 15 & 16, 2005
Roger Haroutunian

9. Power:parameters Radiation from vessel
Steal: emissivity (300°K)
-Assume all power absorbed by cold plate/thermal screen
-Value is overestimated :
-geometry
-thermal screen (Al) with good reflectivity, reducing absorbed
power
Main source of N2 consumption
Thermal damping support : ~ 1,4 W impact/N2 consumption
(conduction) no effect/Moly temperature
November 15 & 16, 2005
Roger Haroutunian

10. Power:parameters
Strip conduction From cold entry point (spacer) to Molybden:
modifies the operating temperature
From room temperature to cold entry spacer
N2 consumption
Heating Resistors from 0 to 500 mW T regulation
Power for H1RG ~ a few mW
Vacuum heat power linear with pressure
WARNING / uncontrolled vacum loss: no safety
slow vaccum loss : no safety system implemented
November 15 & 16, 2005
Roger Haroutunian

11. Thermal control M(Moly) =370g Heating resistors P_Moly~100mW(90K)
November 15 & 16, 2005
Roger Haroutunian

12. N2 Consumption 1.4 l TOTAL to cool cold plate to ~140K
0.2 l/h to stabilize
the temperature
Insensitive to Power
flux on Moly
Cooling
stopped
November 15 & 16, 2005
Roger Haroutunian

13. Connecting strips Kapton fiberglass spacers(4022)
1 spacer on cold plate
1 spacer on thermal screen
Red curve : fiberglass temperature
Perfect thermal contact assumed
November 15 & 16, 2005
Roger Haroutunian

14. T variation rate tuning
Molybden Mass
Damping spacers A/L
Les paramètres d’ajustement principaux sont
- Les dimensions des amortisseurs
- Masse du support de molybdene
November 15 & 16, 2005
Roger Haroutunian

15. Summary Temperature variation rate < 1K/mn
Requested range covered (90K to 140K)
Heating power from 0 to 500mw
(>> electronic power)
Molybden mass will ensure appropriate stability
System can be tuned if needed
Moly mass increased to 500g
Size of damping spacers adapted
November 15 & 16, 2005
Roger Haroutunian