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HSO SORPTION COOLERS Lionel DUBAND

HSO SORPTION COOLERS Lionel DUBAND L. Clerc, D. Communal, M. Dubois (BV), JL. Durand, E. Ercolani, L. Guillemet, N. Luchier, L. Miquet, R. Vallcorba Service des Basses Températures CEA-SBT (CEA/DSM/DRFMC/SBT). MODELS - GENERAL STATUS. STRUCTURAL MODEL (STM). • No thermal capabilities

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HSO SORPTION COOLERS Lionel DUBAND

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  1. HSO SORPTION COOLERSLionel DUBAND L. Clerc, D. Communal, M. Dubois (BV), JL. Durand, E. Ercolani, L. Guillemet, N. Luchier, L. Miquet, R. Vallcorba Service des Basses Températures CEA-SBT (CEA/DSM/DRFMC/SBT)

  2. MODELS - GENERAL STATUS

  3. STRUCTURAL MODEL (STM) • • No thermal capabilities • • Main goal : validation of Kevlar suspension system • • Dummy cooler heart made out of aluminum • (was not intended to be • vibration tested cold)

  4. VIBRATION TESTS - STM WITH KEVLAR 0.5 and 0.3 mm KEVLAR FAILURE Sinus [0 - 100 Hz] X : 40 G Y, Z : 25 G Random [0 - 2000 Hz] X : 14 G rms Y : 11.3 G rms Z : 9.9 G rms Visual inspection : rupture of one "stitch" CSL ROOM TEMPERATURE TESTS high G level Lateral motion Rubbing & rupture Analysis : Note : lowest resonant frequency > 450 Hz Kevlar 34 Replaced by Kevlar 11 (Ø 0.29 mm to 0.5 mm) • Stronger • easier to manipulate • Nominal tension x3 Solution at this stage All susbsequent tests successfully passed with larger Kevlar cords

  5. VIBRATION TESTS - SUMMARY OF RESULTS Both units mounted PACS like. Only X axis tested Input spectrum Random [0 - 2000 Hz] 20 - 200 Hz : + 3 dB 200 - 250 Hz : 0.28 g2/Hz 250 - 2000 Hz : - 12 dB ≈ 8.06 G rms Sinus [0 - 100 Hz] : 30 G Lower levels RAL LOW TEMPERATURE TESTS SPIRE STM mounted with 0.29 mm Kevlar strings on evaporator side Low temperature : 82 K Frequency shift • Tests at room T :  • Tests at 82 K :  • Tests at room T Once units warm :  But ∆ = 116 Hz NOTE : same signature after warm up at room T

  6. FREQUENCY SHIFT ? Cold V test on STMs does not make sense • Structure = Ta6V (thermal contraction 1.5 10-3) • Kevlar strings (-3 10-3, new value at -1.7 10-3 since then) • Aluminum body for cooler heart (4 10-3) External strings ≈ 2.9 DaN Tensioning at room T 12 DaN At low T Internal strings ≈ 13.9 DaN

  7. VARIATION OF RESONANT FREQUENCIES WITH TEMPERATURE tension dependent ? Hysteresis between tensioning - detensioning define a "dynamic" Young’s modulus in real situation Y300K = 38.7 TE-0.018 + 3.4 TE0.516(GPa) Assuming average fit for up and down (TE : tension in N) Real situation : string + pulleys

  8. CRYOGENIC QUALIFICATION MODEL (CQM) Both CQMs qualified SPIRE : 290µm/500 µm strings PACS : all strings 500 µm

  9. QUALIFICATION PROGRAM Thermal tests (HCR#1) 5 days 80°C bake out Thermal tests (HCR#2) Room T vibration tests Thermal tests (HCR#3) Thermal tests Nominal perf.

  10. EXPERIMENTAL SET-UP

  11. RECYCLING PHASE - CRYOSTAT TILTED AT 60°

  12. HEAT FLOWS - CRYOSTAT TILTED AT 60° Note : use of the full 120 mn for the recycling phase, to get a flowing power as low as possible at the end of the phase

  13. CONVECTIVE EFFECTS - CRYOSTAT TILTING Possibly down to 14 mW

  14. VIBRATION TESTS - CSL JULY 2-4 2003 Input levels

  15. CSL CQM VTESTS (RT) - INSTRUMENTATION • Accelerometers : • two pilotes on adaptating plate • structure • evaporator cold tip • evaporator switch base • pump switch base

  16. MAIN RESULTS No major failure (lost one wire on HS redunded - CQM PACS) [800 - 1500 Hz] [125 - 140 Hz] [300 - 360 Hz] [300 - 650 Hz] XX / YY : XX : resonant frequency YY : corresponding G (0.5 G excitation)

  17. COOLING POWER CURVES - HEALTH CHECK REPORT No significant difference between HCR#1, HCR#2 and HCR#3 or rather results consistent within ± 5 mK HCR#1 - CQM PACS : Parasitics estimated at 12 µW ± 10% [Case 1.62 K level 0 - 2 K level 1] Prediction ≈ 10 µW

  18. AUTONOMY TESTS Nominal conditions : L0 = 1.7 K - L1 = 4 K • First test with 10 µW applied load 45 hours @ 290 mK CQM SPIRE Not within predictions 35 hours @ 291 mK CQM PACS • tests with various applied loads Tests performed in same conditions every time 1/time versus Papplied m0.L = (Papplied + Pparasitics).time Straight line : m0 and parasitics m0: amount condensed / L: latent heat

  19. AUTONOMY TESTS - MORE DATA • Extra parasitic of 8 to 10 µW • Cooler undercharged by 10% Analysis of data

  20. EXTRA PARASITIC LOAD ANALYSIS - KEVLAR ? Remark : results eliminate possibility of parasitic coming from contact with snubber OK at least in the range [2 K - 10 K]

  21. EXTRA PARASITIC LOAD ANALYSIS - KEVLAR & TITANIUM Cooler operated without strap between switch and evaporator Note : cycle limited to 2.2 K / 35 K From experimental data : 6.5 µW Predicted : 6.7 µW Parasitic load

  22. EXTRA PARASITIC : GAS GAP HEAT SWITCH + STRAP

  23. LATEST RESULTS - CQM Reset to nominal (strap not gold plated) Nominal conditions : L0 = 1.7 K - L1 = 4 K With 10 µW applied load 47 hours @ 291 mK Analysis of data • Parasitic of 13 µW (predicted 14 µW) CQM PACS delivered to SAp November 6th

  24. FUTURE ACTIONS Heat switch - FM/FS models • production of a batch (≈ 10) • selection of best ones for cold tip • thermal characterisation procedure revisited • improved strap ON going thinking • geometry ? • limit the heat flow in case of contact ? • strap : flexibility

  25. YOUNG’S MODULUS VERSUS TENSION : IMPACT ON COOLER Sliding ?

  26. KEVLAR TENSION HISTORY Note : CQM PACS not retensioned at delivery (SAp demand)

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