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Particles and Fields Package Pre-Ship Review October 30,31, 2012 Section 15 STATIC James McFadden

Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission. Particles and Fields Package Pre-Ship Review October 30,31, 2012 Section 15 STATIC James McFadden. STATIC Team. Instrument Lead: James McFadden Electrical:

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Particles and Fields Package Pre-Ship Review October 30,31, 2012 Section 15 STATIC James McFadden

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  1. Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission Particles and Fields Package Pre-Ship Review October 30,31, 2012 Section 15 STATIC James McFadden

  2. STATIC Team Instrument Lead: James McFadden Electrical: Robert Abiad, Ken Hatch, Dorothy Gordon, Chris Tiu, Peter Berg, Selda Heavner Mechanical: Greg Dalton, Greg Johnson, Paul Turin, Chris Smith Testing: Onno Kortmann, Mario Markwordt

  3. Summary of Science Requirements STATIC Science Objectives and Requirements • Thermal Ionospheric Ions (0.1-10 eV) • - >1 eV due to RAM velocity (~4 km/s), peak flux at ~2-3 eV • - densities of 105/cm3 require both attenuators • - densities of 103-104/cm3 require single attenuator • - resolve 3D angle distribution requires ~10-20 deg sensor resolution • - resolve parallel temperature down to ~0.1 eV requires ~1 eV • Suprathermal Ion Tail – Conics (5-100 eV) • - >5 eV ions with escape velocity • - expected fluxes similar to Earth’s aurora • - as RAM ions drop below ~102/cm3, switch off attenuators • Pick-up Ions (100 – 20,000 eV) • - tenuous flux may require long integrations • - flux generally maximum perpendicular to solar wind V and B • - optimal measurements may require rotation of APP • - instrument should not saturate in magnetosheath

  4. STATIC Block Diagram Starting from the top: 1) Ions are energy selected by the analyzer 2) Ions post accelerated by 15 kV 3) Ions penetrate Start foil producing e- 4) Start electrons accelerated and deflected to the MCP producing signal in Start anodes 5) Ions traverse 2 cm and penetrate Stop foils producing e- 6) Stop e-, accelerated by ~10 kV, penetrate thick foil (-4-5 kV), strike MCP producing signal in Stop anodes 7) Protons penetrating Stop foil are captured by thick foil before reflecting 8) Heavy ions may reflect before thick foil, due to energy losses in foils, but have high efficiency for foil e- production 9) Separate delay line anodes for Start and Stop signal allows both position and time coincidence for rejection of noise. 10) Digital interface board decodes and stores event before transfer to PFDPU 11) 4 sec cycle time 64E x 16 Deflections Mechanical Attenuator Electrostatic Attenuator

  5. STATIC has completed calibrations STATIC has two open PFRs STATIC schedule: Vibration 10-31 Thermal Vacuum 11-1 to 11-12 Acoustics 11-13 Magnetics 11-14 Post Environmental functional test 11-15 to 11-21 Status of STATIC

  6. STATIC PFR Status

  7. STATIC PFR Status New PFR --- V-grid noise (~3V) detected in housekeeping. Open V-grid is a 0-25 V signal applied to an attenuator grid in sensor aperture. When the capacitive (~1nF) load of the sensor is added to the V-grid output, the drive circuit oscillates (~60 kHz, 3V @ 25V output). Oscillations were detected during calibrations from housekeeping. Sensor operates adequately with oscillations, however there is concern that this may disrupt LP measurements. Solution is to add a 100k series resistor to the harness (work to be performed 10-30). Solution shown to work on the bench. Rework will not impact schedule.

  8. STATIC PFR 119 Detector Background Noise too large Although coincidence logic can remove noise, background noise should be below ~1kHz. Sensor could fly and meet requirements at ~10 kHz background, but would lose sensitivity for tenuous pickup ions. Sensor background is primarily due to field emission, or related ion feedback, associated with the -15 kV high voltage bias of the TOF analyzer. Sensor background noise varied from <1 kHz to >1 MHz during testing. Sensor would operate for extended periods with acceptable background levels then develop noise. Identification of the noise was difficult due to multiple, independent noise sources, some of which only showed up after several tens of hours at HV. Sources of TOF Background Field emission from dust Field emission from carbon foils Field emission from external surfaces Field emission sub-visual contamination Ion feedback from absorbed gas

  9. STATIC PFR 119 Problems Identified and Fixes Implemented: Field emission from dust Changed part placement procedures for clean bench Careful visual inspections with bright lights Careful visual inspection with UV light Field emission from carbon foils Suppression grid added to start foils Kapton tape ribbon covering edges of foil frames Field emission from external surfaces Suppression grids electro-polished Start/Stop foil clamps electro-polished Foil Clamps left bare Al (not gold plated) Edges of TOF foil frames covered in Kapton tape ribbon Field emission sub-visual contamination Run ACC at 15kV (detectors off) for ~48 hrs to burn off Ion feedback from absorbed gas Run ACC at 15kV (detectors off) for ~48 hrs to burn off Monitor ACC current for ~0.5 mA variations Current status: After the above fixes were implemented, the sensor was placed in high vacuum on 10-13 and pumped for 2 days. On 10-16, STATIC HV was turned on and ACC raised to 13 kV – no noise. At 15 kV, low level noise appeared and continued to grow over ~10 min. Noise remained as HV was lowered to ~10 kV. Detectors were switched off and ACC raised to 12 kV where ACC current variations indicated ion feedback discharges. On 10-17, HV was raised to 15 kV and after several hours the ion feedback discharges stopped. After one day additional scrubbing at 15 kV, noise remained low through out additional calibration testing (>130 hrs).

  10. PF Level 3 Requirements

  11. STATIC Calibration (PF 60,61) Sensor Energy-Angle resolution tested with 2000 eV ion beam, no Attenuator. Sensor Energy and Angle resolution as expected. Ion gun beam broadens angular response slightly. ~1o offset in beam center consistent with alignment error. H+ and H2O+ have identical response. Angle H+ Energy Resolution: ~13.5% (Sim ~13%) O+ Mass bin Angle Resolution: ~8o (Sim ~7o)

  12. STATIC Calibration (PF 60,61) Sensor Energy-Angle resolution tested with 2000 eV ion beam, with Mech Attenuator. Sensor Energy and Angle resolution with Mech Attenuator as expected. Same ~1o offset in beam center. Energy and Angle response narrower as expected. H+ and H2O+ have identical response. Angle H+ Energy Resolution: ~9% O+ Mass bin Angle Resolution: ~4o

  13. STATIC Calibration (PF 60,61) Sensor Energy-Angle resolution with 11.5 eV ion beam, with Electrostatic Attenuator. Sensor Energy and Angle resolution with E-static Attenuator as expected. Same ~1o offset in beam center. O+ Energy and Angle response as expected for 1 eV beam – (0.135)2 + (1/11.5)2 )1/2 = 16% H+ response is broad due to dissociation energy upon H2O ionization. Angle H+ Energy Resolution H2O+ : ~17% O+ Mass bin Angle Resolution: ~8o

  14. STATIC Calibration (PF 62) 360o FOV, No Attenuators Sensor meets requirement (PF62) for 360o FOV in detection plane without attenuators Ion gun energy fixed 2000 eV Sensor sweeping energy 1500 to 2500 eV. Sensor rotated 360o about symmetry axis. Sensor deflectors are off. Minima between peaks are due to modulation by aperture posts, coupled with a narrow energy parallel beam. Rot Angle Counts H+ Energy O+ Energy Mass bin

  15. STATIC Calibration (PF 62,55,56) 360o FOV, Mechanical Attenuator Sensor meets requirement (PF62) for 360o FOV in detection plane. Attenuator provides factor of 100 reduction in RAM direction. Ion gun energy fixed 2000 eV Sensor sweeping energy 1500 to 2500 eV. Sensor rotated 360o about symmetry axis. Sensor deflectors are off. Rot Angle Counts H+ Energy O+ Energy Mass bin

  16. STATIC Calibration (PF 55) Dynamic Flux Range – Electrostatic Attenuator (x 0.1) Sensor sweeping energy: 7 to 20 eV Gun 11.5 eV beam Vgrid swept from 25 V Sensor rotated across all anodes Sensor sweeping energy: 7 to 20 eV Gun 11.5 eV beam Vgrid swept from 0 to 25 V Cutoff at Vgrid~18V

  17. STATIC Calibration (PF 62) Sensor exceeds requirement (PF62) for FOV extending 60o out of detection plane. Actual FOV extends 90o (+/-45o) out of plane. Ion gun energy fixed 2000 eV Sensor energy fixed 2000 eV Sensor rotated +/-45 deg out of plane. Sensor deflectors are stepped through 16 deflector angles: -45,-39,…,-3,3,9,…39,45 Minima between peaks are due to energy-angle response with a fixed energy beam and discrete deflection steps. Angle Counts Def bin Mass bin

  18. STATIC Calibration (PF 59) Energy Range 4000 to 20 eV Sensor exceeds requirement (PF59) for energy range. Capable of ~30keV by design. HV tested to 30 keV. Beam tested to 4 keV. Ion gun stepped from 4 keV to 20 eV with fixed beam direction Sensor in pickup ion sweep mode sweep 30 keV to 0.5 eV. Low energy shift of O+/H+ are due to gun issues. Low energy measurements require special gun configuration seen in next slide. Gun Energy H+ Energy O+ Energy Mass bin

  19. STATIC Calibration (PF 59) Sensor meets requirement (PF59) for low energy (1eV) range. Testing at low energy shows sensor resolves cold O+ and reveals response of ion gun. Ion gun stepped from 15 to 0 eV. Ions ~0.5 eV higher in energy due to ionization chamber bias. Sensor in low energy sweep mode 15 eV to 0.5 eV. Filament Gun ionizes residual gas in chamber, primarily water. Ionization chamber has 1 V bias gradient to eject ions. H+ is produced from H2O dissociation. Dissociation energy (~5eV) goes to H+ due to conservation of momentum. Water peak (H2O+, HO+, O+) is narrow. Low energy water tail due to scattering and ions produced outside the ionization chamber. Energy Range 15 to 0.5 eV Gun Energy H+ Energy O+ Energy Mass bin

  20. STATIC Calibration (PF 57,58) STATIC Mass resolution (M/dM >2) and Mass range at least 1-44 AMU O+,H2O+ 20 eV 7eV H+ Counts At 11.5 eV N2+,O2+ H2+ Mass bin (0-63) Time of Flight (ns) H+ 2.5 keV 1.5 keV Counts At 2 keV O+,H2O+ N2+,O2+ CO2+ H2+ Mass bin (0-63) Time of Flight (ns)

  21. STATIC Calibration Pickup Mode, 50 eV beam – 42 hr test, nominal operations Before After

  22. STATIC Ready for Environmental Vibration Test Procedure signed Thermal Vac Procedure reviewed Acoustic Test Procedure signed Final build documentation final build 10-30 PFRs analysis complete, solutions understood need to update paperwork SWIA has paved the way for STATIC vibration and thermal vacuum testing SWIA circuit board mounting design changes have been applied to STATIC SWIA Thermal Vac procedures and hardware nearly identical. STATIC carbon foils have already undergone acoustic testing and thermal baking Sealed sensor head minimizes acoustic noise access to carbon foils. Post environmental testing should be faster since all procedures have been run

  23. STATIC Resources MASS: 3.3 kg LV Power: ~94 mA @28V Average LV+HV Power (sweeping, temp dependent): ~135-150 mA @ 28V ~3.8-4.2 Watts

  24. STATIC Calibration (PF 62,55,56) 360o FOV, Mechanical Attenuator Sensor meets requirement (PF62) for 360o FOV in detection plane. Attenuator provides factor of 100 reduction in RAM direction. Ion gun energy fixed 2000 eV Sensor sweeping energy 1500 to 2500 eV. Sensor rotated 360o about symmetry axis. Sensor deflectors are off. Counts Rot Angle

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