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PACS – IHDR PhFPU Design. J. Martignac CEA/DSM/DAPNIA Service d’Astrophysique. INTRODUCTION. PhFPU Requirements BFP & PhFPU : - Design -Thermal & Grounding Scheme - Validation & Qualification Critical Items. PhFPU Requirements. Mass around 7 kg.
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PACS – IHDRPhFPU Design J. Martignac CEA/DSM/DAPNIA Service d’Astrophysique
INTRODUCTION • PhFPU Requirements • BFP & PhFPU : - Design -Thermal & Grounding Scheme - Validation & Qualification • Critical Items
PhFPU Requirements • Mass around 7 kg. • External Envelope & Mechanical I/F according to the Doc. : PACS-KT-ID-005-iss.4 • Admissible Load according to the Doc : PACS-KT-AN-005-iss.2 • Thermal Consumption : • - to 12µW at 300mK • - to 4,3mW at 2K without the Cooler
BFP : Design • The BFP is mainly composed by 5 Sub-assemblies: • the mechanical structure, • the focal plane at 300 mK, • the 300mK thermal strap • the 2K circuit buffer, • the envelope.
Cooler Harness Holder Connector Panel 4K Structure PhFPU : Design • The PhFPU is mainly composed of 8 Sub-assemblies: • the 4K Structure,
R & B BFPs Holder Stainless Steel Insulating Tubes Voltalef Insulating Spacers PhFPU : Design • the 2K Structure,
R BFP R&B BFP Filters Boxes R&B 2K/4K Ribbon Cables B BFP PhFPU : Design • the two BFPs Red & Blue ,
3He Cooler Harness 3He Cooler L0 Straps Baffling Shield Covers PhFPU : Design • the 3He sorption Cooler
R&B Copper Braid R&B BFPs Thermall I/F 300mK Thermal Strap Kevlar wires suspension to the 2K Stray light Baffling Copper Braid Kevlar wires suspension to the 4K 3He Cooler Thermal Interface PhFPU : Design • the PhFPU 300mK Thermal Strap from the cooler to the BFPs
R&B BFP L0 I/F 2K Feedthrough (by KT) Copper Braids Stray Light Baffle L0 Strap I/F PhFPU : Design • the 2K Thermal Strap,
2K Baffle 4K Baffle PhFPU : Design • & the Baffles.
PhFPU : Design PhFPU assembly • Status: • Mechanical I/F: OK • Optical I/F: SOAM (KT) • Parts Manufacturing: OK • Integration Tools: OK • Black Paint: in progress • Full Assembly: First Time • Thermal: to be validated
élec=2,8mW (B&R BFP) PhFPU 2K I/F struct=0,8mW flex=0,5mW R6 Rc4 PhFPU 4K Structure PhFPU R3 Feedth.=0,5mW TBC by KT Rc3 R1 Evap. Switch I/F T 2K Evap. Rc1 h0,12W.K-1 R2 Pump Switch I/F Pump. Rc2 h0,075W.K-1 PhFPU Thermal Equivalent Scheme Global Thermal budget on the L0 level: - 4,1mW + 0,5mW* *:(TBC by KT) L0 Straps manufacturing is under responsibility of Astrium
PhFPU Structure @ 4K BFP Housing @ 2K Evap. Pump Cooler Structure @ 4K Optical Bench Space Scraft L0 Thermal Straps He Tank PhFPU Grounding scheme • The PhFPU grounding configuration is like represented: • one shield @ 2K close to the bolometers and signal • one shield @ 4K performed by the outer PhFPU and Cooler Structure • the electrical insulation between the two shields are performed by: • Voltalef parts at the Structure level • 0,1mm layer of STYCAST 1266 between copper foils at the Thermal Strap level (300mK & 2K)
Validation & Qualification • Succesful Warm vibrations have been done : • on a BFP Structure alone • at the PhFPU level • & at the Instrument level A new PhFPU SM has been build for the Cold vibration campaign at CSL. The BFP Kevlar suspensions only survived to the first two axis (Y & Z), and a breakage occured at the beginning of the third run (X). But higher input levels than specified in the IIDA was applied.
BFP : Validation & Qualification – Future Tests New stiffness measurements at 4K will be done on a BFP Structure in two directions : - axial (applied load to the focal plane) - transverse ( // to the focal plane) These tests should be repeated 2 or 3 times on the same Structure to study the thermal cycling influence on the Kevlar wire suspensions. • Cold vibrations are planed : • on a BFP Structure alone • on a BFP equiped with detectors and its complete readout circuit to validate all the interconnections from the detectors to the end of the 2K/4K Ribbon Cable.
PhFPU : Validation & Qualification – Future Tests • A complete PhFPU FEM is complete now with the Cooler & the BFP Kevlar suspensions • Warm vibrations will be done at the PhFPU level to investigate potential coupling between the PhFPU 4K Structure and 3He Cooler: • Cooler SM refurbished with a Titanium core and a functionnal switch linked to a representative L0 Strap: TBC!). • New cold vibrations campaign under negociation (ESA/Inst).
PhFPU Critical Items • Critical: • Qualification at Cold temperature • BFP Kevlar wire suspension • Mechanical load on the Cooler thermal switches I/F • To be validated: • 0,3K Strap thermal behaviour (without & with electrical insulating parts. • Cooler behaviour mounted on the PhFPU (thermal environment)
Progress since IBDR • 3 models of the PhFPU have been built: SMKT, SMKT2 & SOAM • Warm vibrations done succesfully passed at sub-assembly and at instrument level • BFP assembly & integration is now completely stabilised • 2K/4K ribbon cables manufacturing is now under control • PhFPU design is complete, all the parts for the QM are manufactured