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Mechanical Design Presented By Kutty

CZT – Imager. Mechanical Design Presented By Kutty. Design inputs from Mr. Dhanabalan(GD), MID, ISAC Mr. Poddar.P.K,MID,ISAC. Contents. Requirements Design Considerations Various Approaches Design in details Advantages of planned configuration Mass budget Payload at a glance

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Mechanical Design Presented By Kutty

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  1. CZT – Imager Mechanical DesignPresented ByKutty

  2. Design inputs from Mr. Dhanabalan(GD), MID, ISAC Mr. Poddar.P.K,MID,ISAC

  3. Contents • Requirements • Design Considerations • Various Approaches • Design in details • Advantages of planned configuration • Mass budget • Payload at a glance • Conclusion

  4. Requirements.... • Effective Area to be achieved : 1024 cm2 • Temperature range for CZT : -20o C - 0o C • Designing a Collimator with specific angle of collimation Low Energy - 1.5o X 3o HighEnergy - 6o X 6o • Coded Aperture Mask (CAM) Design & Assembly • Alignment of CZT modules with Collimator & CAM • Fixing of CsI Detector & PMT with HV package and alignment with CZT modules • Provision for onboard calibration. • Pointing Accuracy : 0.1o

  5. Design considerations • Functional Aspects • Mass Considerations • Overall Area & Volume of Instrument • Thermal Constraints Methodology Adopted Empirical Design & Optimisation

  6. Approach...... 1. Quadrant wise Design 2. Integrated collimator & Calibration housing 3. Mechanically Integrated & Functionally Quadrant wise Structure Why Quadrant...??? • To achieve required temperature range • Reduced complexity in Electronics • Functional requirement • Ease in Fabrication, Test & Calibration • Time saving in calibration

  7. Quadrant...??? How it looks..?

  8. Starts from the basic input • CZT module Area of each module : 4 cm x 4 cm = 16 cm2 No. of modules to be used to achieve 1024 cm2 = 64

  9. Detector Board Assembly • Detector Board (Cu-in-Cu) • CZT module

  10. Detector Housing CsI Housing CsI Detector PMT(2nos) Light Guide F.E.Electronics Detector Hsg. Assembly

  11. Calibration Housing HV box Alpha box Calibration Housing Assembly

  12. Housing plates H.E.Collimator (Al. + Tantl. + Al) L.E.Collimator (Al.plates) Collimator Assembly

  13. Collimator Assembly procedure Pre-machining of Al. plates Bonding of Tantalum sheet in between Al. plates Final machining of bonded components Assembly

  14. Coded Aperture Mask (CAM) Assembly Coded Mask Mask Holder (Top) Mask Holder(Bottom)

  15. X - Connector Electronics Housing Common Components for Quadrants

  16. Merits 1. Time saving in testing & Calibration 2. Since it is a new area of R & D, making 1/4th of Instrument will save time & money 3. Fabrication & assembly become easier for a single Quadrant 4. Since it is an identical instrument , replacement is possible at any stage in ground level 5. Handling become easier Demerits 1. Structural mass penalty of 10% 2. Rise in overall area by 10% 3. It takes more time for flight model fabrication & Assembly 4. Rework ability become less at space craft level 5. Survival of critical component like FPGA is difficult due to relative motion 1ST ApproachQuadrant wise design

  17. 2nd ApproachIntegrated Structure Assembly of integrated Calibration Housing & Collimator

  18. Merits Elimination of joints Demerits Overall mass increased by 0.5kg due to an additional high energy collimator plate Redundancy of instrument at ground level will be reduced Complexity in fabrication , assembly & testing Replacement or repairing of any single quadrant will affect the whole instrument calibration.

  19. 3rd ApproachMechanically integrated & Functionally quadrant wise structure

  20. Bottom part

  21. Top part

  22. Advantages over other designs…. 1. This gives a robust structure by Design which will increase natural frequency. 2. Payload height is effectively reduced by 70mm by separating Front – end Electronics package will improve frequency level. 3. Improved re-workability in F.E.Electronics at space craft level. 4. Failure rate of critical component like FPGA will be dropped due to elimination of relative motion. 5. Expected mass saving about 2kg. 6. Elimination of joints, so complexity in assembly and alignment reduced. 7. Time saving in fabrication, assembly & inspection of flight model. 8. Time saving in calibration of collimator

  23. 9. Integrated HV package with CsI crystal 10. Handling become easier Penalty of this Approach… 1. Complexity in fabrication due to intricate machining

  24. CZT-Imager....

  25. Mass Distributionof CZT-Imager

  26. Name of Component Material Mass in gms Mass Savings by optimisation Mask holder (Top) Mg.Alloy 18 Mask holder (Bottom) -do- 55 Collimator hsg.plates (4nos) Mg.Alloy 800 100 Calibration hsg. Mg.Alloy 330 50 Window Structure -do- 40 H.V.Box -do- 115 25 Alpha box -do- 115 25 CsI hsg. -do- 250 250 Detector hsg. -do- 430 30 Det.hsg.cover -do- 200 100 Mass Distribution Structural Mass for one Quadrant Total = 2353 (580) For 4 Quadrants = 9412gms (2240)

  27. Coded Mask 130 H.E.Col.Tantal.Plates (6nos) 1400 CZT modules (16nos) 1080 CsI crystal 4300 800 F.E.Electronics 1200 Other Electronics 150 Potting compound 200 Connectors & Cables 250 Detector Board 1500 500 H.E.Col plates (12nos) 1440 700 L.E.Col.plates(64nos) 700 Fixed Mass for one quadrant Total = 12350 (2000) For 4 Quadrants= 49400 gms (8000)

  28. X-Connector 135 Electronics hsg. 1125 Common Components • Total = 1260 • Overall Wt. of CZT-Imager = 60072 gms • With Wt. reduction = 49832 gms • Structural mass = 8432 gms = 16.9% of overall Mass

  29. Payload at a glance... • Effective area : 1000cm2 • Overall Dimension : 500mm x 500mm x 700mm • Mass : 49.8 kg • Pointing accuracy : 0.1o • Collimation achieved : H.E - 5.7o x 5.7o L.E - 1.4o x 2.9o • Temp. range for CZT : -20oC - 0oC

  30. Approach for Realising CZT-Imager Analysis & optimisation of 3rd Approach • Analysis for Natural frequency • Mass optimisation • Review of functional aspects Fabrication of lab model • To establish & qualify the process • To qualify CZT modules • To establish an assembly procedure Fabrication of an Instrument with an area of 64 sq.cm • To test & evaluate the configuration Fabrication of structural model • To qualify all the components

  31. Open Issues… • CZT module qualification • Qualification of CsI crystal with PMT • Realising collimator accuracy & Alignment with CAM • Qualification of electronics package with critical component like FPGA

  32. Mechanically integrated & Functionally Quadrant wise Design have an edge over other alternative designs, it is decided to adopt this approach for making CZT-Imager. Overall Mass can be reduced by incorporating various suggestions given by ISRO experts Based on analysis results Payload can be optimised. A Collimator model should be realised and qualified Conclusions

  33. Project Team and experts from Mechanical, Structural & Thermal Divisions of ISAC Thanks to.........

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