Mech Systems Proposed EMI Modifications

1. Mech Systems Proposed EMI Modifications Marc Campell 9/2/03

2. EMI Skirt on Grid Mechanical Systems EMI Impacts

3. Finding 3 - E-Nickel on Grid • Issue: Electroless nickel on Grid at CAL (and TRK, ACD & Radiator) interfaces is “better” than alodine on Aluminum • Implementation plan is the concern • Sequence of Grid plating, insert installation and higher level drilling operations; • Grid requires high emissivity outer walls and • Masked areas for bonding operations • Grid has 2000+ holes so masking/plugging holes is non-trivial Mechanical Systems EMI Impacts

4. CAL – Grid Interface Mechanical Systems EMI Impacts

5. Finding 3 - E-Nickel on Grid (cont) • Impacts • Grid Mfg plan • Grid drawing note callout and masking details on drawing • Schedule • 4 x 4 Grid Mfg plan due by early Sept • 4 x 4 Drawing due mid-Sept • Drop dead decision date mid Oct (with impacts) Mechanical Systems EMI Impacts

6. Findings 5 & 6 – EMI Shield Butt Joints • Issue: Butt joints may leak • 2 types of butt joints - edge on and flange as shown • EMI skirt to X-LAT plate • EMI skirt to Grid • EMI skirt to EMI skirt • EMI skirt to connector patch panel • Possible improvements • Tongue & groove joint • EMI gasket in groove • Conductive bond between components Mechanical Systems EMI Impacts

7. EMI Skirt Joints Mechanical Systems EMI Impacts

8. EMI Skirt Joints 2 Mechanical Systems EMI Impacts

9. 5 & 6 – EMI Shield Butt Joints (cont) • Tongue and groove or gasket • Looks difficult to implement on grid especially near S/C interface & other Grid shear bosses • Plausible for some skirt to skirt joints and some areas of the X-LAT plate to EMI skirt away from heat pipe exits • Radiator Mount Bracket & Heat Pipe Patch panels could be conductively bonded to each other & the Grid (no planned removals after Grid Assy) Mechanical Systems EMI Impacts

10. 5 & 6 – EMI Shield Butt Joints (cont) • Impacts • 6 (x 2) skirt drawings (90 Mhrs) • Grid drawing including possible redesign (& analysis?) of shear bosses (80-120 Mhrs) • X-LAT plate is awaiting final definition • Schedule • EMI skirt drawings needed late Sept • Being analyzed now • Consider EMI test of EMI skirt box to isolate specific problem areas & to define magnitude of problem Mechanical Systems EMI Impacts

11. Finding 7 – 3 Piece X-Lat Plate • 3 vs 1 piece X-LAT trade is currently under study • Issues • Alignment of X-LAT fasteners to E-box inserts for direct bolting of X-LAT plates • LM tooling impacts & VCHP alignment • Tolerance of butt joint is an issue at EMI skirts • LM cost & producibility • Schedule • X-LAT design finalized mid-late Sept Mechanical Systems EMI Impacts

12. 3 X-LAT Plates Mechanical Systems EMI Impacts

13. X-LAT Butt Joint Mechanical Systems EMI Impacts

14. Finding 9 – Venting of EMI Box • 2 choices • 1) Vent through X-side EMI skirt(2-4 in2 req’d) • 2) Vent through CAL baseplate crenulations, past TRK’s and out between ACD to Grid gap • 1) is straight forward, but effective 550 kHz filtered vent must be designed (commercial filters for 10’s MHz to GHz) • 2) is convoluted path past TRK & CAL cables • If analysis is not robust, a test may be required Mechanical Systems EMI Impacts

15. Finding 9 – Venting of EMI Box (cont) • Impacts • 2 EMI skirt drawings (20 Mhr) • Design, develop & test a filter/vent (120 Mhr) • Schedule • EMI skirt drawings late Sept Mechanical Systems EMI Impacts

16. Finding 11a – Radiator Level EMI Test • Issue – S/C regulated power and LAT heater control box will send noise down to strip heaters mounted on Radiator which may emit noise • LM can be directed to do best practices for EMI shielding of TCS components • LM can’t do this test without S/C regulated power & LAT heater control boxes • Finding a problem at the LAT level test is too late • Needs to be worked at SLAC upfront Mechanical Systems EMI Impacts

17. Finding 11a – Radiator Level EMI Test (cont) • Impact • LM did not cost this test in their Phase II proposal • Cost & schedule impacts to Radiator delivery • Schedule • Radiator is on a day for day slip until spec gets released including resolving this issue Mechanical Systems EMI Impacts

18. Finding 11b – LAT Level Radiator EMI Test • Radiators should be installed for LAT level EMI test • Agree • I&T needs to access impacts to current flow • S/C regulated power needs to be available • Systems Engr. needs to revise LAT Test Plan Mechanical Systems EMI Impacts

19. Finding 12 – Radiator – Grid Interface • Current design has G-10 spacer between Radiator and its mounting brackets to limit heat leak into Radiator (in survival mode) to less than 5 watts • This electrically isolates the 2 parts • 2 options • Ti spacers with reduced area &/or increased thickness • G-10 spacers wrapped in thin foil Mechanical Systems EMI Impacts

20. Radiator Mount Brackets Mechanical Systems EMI Impacts

21. Finding 12 – Radiator – Grid Interface (cont) • Impacts • LM needs to analyze these options for thermal & structural performance • Schedule • LM waiting to fab Mechanical Systems EMI Impacts

22. Back ups Mechanical Systems EMI Impacts

23. EMI Box +Z up Mechanical Systems EMI Impacts

24. EMI Box –Z up Mechanical Systems EMI Impacts

25. X-LAT Joint Mechanical Systems EMI Impacts