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

Mechanical Systems EMI Impacts2 EMI Skirt on Grid

Mechanical Systems EMI Impacts3 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 holes so masking/plugging holes is non-trivial

Mechanical Systems EMI Impacts4 CAL – Grid Interface

Mechanical Systems EMI Impacts5 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 Impacts6 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 Impacts7 EMI Skirt Joints

Mechanical Systems EMI Impacts8 EMI Skirt Joints 2

Mechanical Systems EMI Impacts9 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 Impacts10 5 & 6 – EMI Shield Butt Joints (cont) Impacts –6 (x 2) skirt drawings (90 Mhrs) –Grid drawing including possible redesign (& analysis?) of shear bosses ( 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 Impacts11 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 Impacts12 3 X-LAT Plates

Mechanical Systems EMI Impacts13 X-LAT Butt Joint

Mechanical Systems EMI Impacts14 Finding 9 – Venting of EMI Box 2 choices –1) Vent through X-side EMI skirt(2-4 in 2 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 Impacts15 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 Impacts16 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 Impacts17 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 Impacts18 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 Impacts19 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 Impacts20 Radiator Mount Brackets

Mechanical Systems EMI Impacts21 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 Impacts22 Back ups

Mechanical Systems EMI Impacts23 EMI Box +Z up

Mechanical Systems EMI Impacts24 EMI Box –Z up

Mechanical Systems EMI Impacts25 X-LAT Joint