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Thermal Control of IR detector

Thermal Control of IR detector. Roger Haroutunian (IPNL,Lyon) CNRS (IN2P3,INSU) FRANCE. Specifications of elements. Main specifications of thermal elements Temperature changes < 1 °/mn Range of variation from 90K to 140K Stability. Overall view. COLD PLATE. TROUGHPUT SPACERS

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Thermal Control of IR detector

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  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 Roger Haroutunian

  3. Overall view COLD PLATE TROUGHPUT SPACERS (for strips) THERMAL SCREEN Roger Haroutunian

  4. Thermal control Thermal damping Roger Haroutunian

  5. Thermal control • Heat Sources/Sinks • 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 plate9.2W • Neglected • N2 Transfer lines • Cold finger for detector protection against dust • Kapton conduction • Detector and electronic 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. ) Roger Haroutunian

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

  8. Input power (Impact/Moly support) Roger Haroutunian

  9. Power:parameters Radiation from vessel Steal: emissivity 0.11 (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 Roger Haroutunian

  10. Power:parameters • Strip conductionFrom cold entry point (spacer) to Molybden: • modifies the operating temperature • From room temperature to cold entry spacer • N2 consumption • Heating Resistorsfrom 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 Roger Haroutunian

  11. Thermal control M(Moly) =370g Heating resistors P_Moly~100mW(90K) P_Moly~500mW(140K) 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 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 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 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 Roger Haroutunian

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