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Particles and Fields Package Pre-Ship Review October 30 -31, 2012

Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission. Particles and Fields Package Pre-Ship Review October 30 -31, 2012 14 - SWEA (Solar Wind Electron Analyzer) D. L. Mitchell and the SWEA Team. SWEA PSR Outline. Overview Environments Issues Plan Forward. SWEA Resource Update.

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Particles and Fields Package Pre-Ship Review October 30 -31, 2012

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  1. Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission Particles and Fields Package Pre-Ship Review October 30 -31, 2012 14 - SWEA (Solar Wind Electron Analyzer) D. L. Mitchell and the SWEA Team

  2. SWEA PSR Outline Overview Environments Issues Plan Forward

  3. SWEA Resource Update Current draw with simulated science operation Test with fully integrated FM instrument in vacuum chamber NR and MCP HV’s on, analyzer and deflector sweeps enabled Test pulser on to generate counts Current draw on 28-V primary supply: 35.2 mA (mean), 52.0 mA (peak) Measured Power: 0.986 W (mean), 1.456 W (peak) CBE Power: 1.074 W (PDR), 0.992 W (CDR) Allocation: 1.240 W Measured Mass: 1.773 kg Measured in pre-environments flight configuration Instrument will be reweighed in final flight configuration Expect very minor changes due to top cap redesign Min: 58 mA, Max 90 mA Mean 62 mA

  4. SWEA Calibration Status Because of PFRs 59 and 122, no calibrations have been performed since PER.

  5. SWEA PFR Status

  6. SWEA Vibration – Aug 17, 20 • SWEA Satisfied Vibe Success Criteria • Pre and Post Sine survey: < 3% freq. shift; < 30% amp. change • First natural freq. > 50 Hz • No loose fasteners or hardware deformations • Pass post-vibe functional (no HV) • However, subsequent operation and inspection revealed vibe-related issues • Two issues observed in TVAC likely occurred during vibe: • Cover actuation on side B failed because of a short on the Digital board (PFR 116) • Contamination in the analyzer and on the MCP by metallic particulates generated by metal-to-metal rubbing of the closed top cap against the outer hemisphere during vibe (PFR 122) • Vibe likely contributed to a third issue: • Cracked and flaking tinning on 180-deg bends in the protection diodes on the Anode board (PFR 122)

  7. SWEA TVAC – Aug 21 to Sep 1 Cycle Number: 1 2 3 4 5 6 7 8 LPT LPT LPT LPT LPT CPT Hot Survival/Balance Bake-Out Open Cover Break Vacuum: Reset Cover, LPT LPT HV On HV On Reconfigure to I/F to EM PFDPU Open Cover LPT LPT LPT LPT CPT CPT Cold Survival/Balance PFR 122 (Sep 1) PFR 116 (Aug 25)

  8. SWEA TVAC Issues • Failed cover opening due to short in side B Actuator circuit (PFR 116) Repaired by cutting traces, installing jumpers, and inserting PEEK washers under connector stand-offs PEEK washers Actuator B trace

  9. SWEA TVAC Issues • Transients and discharges during MCP ramp up (PFR 122) – 1 Sep 2012

  10. SWEA TVAC Issues • Diagnostics following PFR 122 events revealed that MCP HV exhibited a sawtooth pattern during ramp up and steady operation • Expect a sinusoidal oscillation, as observed before vibe/Tvac • Problem traced to a failed VMI multiplier on the HVPS board • Multiplier was replaced and normal function was restored • Tinning on protection diodes on Anode board was cracking and peeling • Diodes replaced with surface mount equivalents • SWEA analyzer disassembled and inspected on Oct 19-21 • Contamination found on inside the analyzer and on the MCP from at least two sources: • fibers from clean room wipes intended to protect the MCP during soldering operations on the Anode board • metallic particles from metal-to-metal rubbing of the top cap against the outer hemisphere during vibe • Analyzer was cleaned and reassembled • Top cap has been redesigned with aluminized rubber gasket (fabricated, but not yet installed or tested)

  11. SWEA TVAC Issues Surface mount equivalents (test on spare board) Cracked tinning on vertically mounted protection diode All vertically mounted protection diodes on the FM Anode board have been replaced with surface mount diodes.

  12. SWEA TVAC Issues Metal-on-metal interface between top cap and outer hemisphere generated metallic particles during vibe. Outer hemisphere Inner hemisphere Wear on top cap Wear on outer hemisphere

  13. SWEA TVAC Issues Debris on Inner Hemisphere Debris on MCP

  14. SWEA TVAC Issues • Redesigned top cap with aluminized rubber gasket • Not yet installed and tested

  15. Discharge Event – 10 May 2012 • Fully assembled FM instrument – PFR 59 (preamp 5 failed) 230-Hz sample rate 10-Hz sample rate

  16. Discharge Event – 5 Oct 2012 • FM pedestal and analyzer side by side, with repaired FM1 HVPS before analyzer disassembly 230-Hz sample rate 115-Hz sample rate

  17. Discharge Event – 24 Oct 2012 • FM pedestal and analyzer side by side, with repaired FM1 HVPS, after analyzer disassembly and cleaning 230-Hz sample rate 115-Hz sample rate

  18. Discharge Event – 26 Oct 2012 • Same configuration as 24 Oct, except with kapton disc inserted between HVPS and shield board) 230-Hz sample rate 115-Hz sample rate

  19. Successful Operation: 27-28 Oct 2012 • Same configuration as 26 Oct, except with spare HVPS (FM2) • 17 hours, 24 MCP HV ramps, no discharges Normal scrubbing of recently cleaned MCP

  20. SWEA – Plan Forward Oct 30-Nov 1 Flight-like build Nov 2-4 Chamber functional, verify no major calibration changes Nov 5-6 Add new top cap Nov 6-8 Chamber functional, verify no major calibration changes Nov 9 Vibe Nov 10-15 Thermal Vac (4 cycles) Nov 16-20 Package I&T Nov 22-30 Post-environments calibration

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