Radiation Effects

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Radiation Effects
New HorizonsShedding Light On Frontier Worlds
Ralph Instrument Critical Design ReviewAug 5
6, 2003

• Tim OConnor
• Ralph Radiation Effects Engineer
• [phone]
• toconnor_at_ball.com

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Parts Radiation Effects Engineering

• Ball ensures radiation hardness of its EEE parts
  through the application of detailed parts
  selection procedures.
• System operability in the mission particle
  environment are verified by incorporating
  part-level single event upset/transient (SEU/SET)
  responses into circuit- and subsystem-level upset
  analyses.

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Radiation Environment Update since PDR

• Release of BATC Radiation Hardness Assurance Plan
  (RHAP)
• Finalizes BATC implementation of APL Component
  Environmental Specification (CES)
• Radiation environment is unchanged since PDR,
  even with removal of RTG shield (due to results
  of sector analysis)
• Radiation transport results confirm low part risk
• Electronics Box BATC shielding model confirms
  that SwRI magnesium box results in Total Ionizing
  Dose (TID) between 10 krad(Si) depending on
  location, consistent with preliminary APL result
  of 6 krad(Si) for generic box
• Risk Reduction BATC model can include part
  location and packaging for lower estimates of TID
  to resolve individual part issues as necessary
• MVIC CCD Detailed radiation transport confirms
  that MVIC displacement damage is below PDR
  estimate in CCD specification and test (TBD
  margin)

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Radiation Requirements

• APL Component Environmental Specification
• Mission-specific radiation environments
• Jovian trapped electrons, solar protons, galactic
  cosmic rays
• RTG neutrons and gamma rays
• All EEE parts must perform within specification
  following exposure to the mission total ionizing
  dose (TID) displacement damage dose (DDD)
• The system shall operate in spite of single
  particle events
• Requires calculation of rates for single event
  upsets (SEUs)
• Single event latchups (SEL) should be minimized
• Single event burnout and gate rupture (SEB and
  SEGR) must be designed out of the system
• Ralph Instrument Specification (RIS)
• Ralph Product Assurance Implementation Plan
• BATC Radiation Hardness Assurance Plan

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Hardness Assurance Methodology

• Ensure hardness via part selection and shielding
• Use only DSCC RHA rated parts and known rad
  tolerant parts everywhere else
• Employ margins for existing radiation test data
• 2X for lot specific data, 4X for non-lot-specific
  data
• Test where necessary to prove rad tolerance
• Perform 3-D shielding transport analyses to
  reduce required radiation tolerance at the part
  level
• Document part hardness via annotated systems
  engineering report
• Perform single event effects (SEE) analyses
• SEU rates and mitigation approaches for all
  susceptible circuits/subsystems

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APL Status - TID

• Parts approved based on direct test data or
  similar part/process test data
• 9 microcircuits (out of 10)
• 1 hybrids (out of 1)
• Enhanced low dose rate susceptibility (ELDRS) not
  ruled out for one part
• OP490 requires ELDRS testing
• Test scheduled for Sep03
• TID parts assessment documented in BATC EEE Parts
  Radiation Effects Assessment (doc TBD)

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APL Status - DDD

• All parts are insensitive to mission displacement
  damage dose levels (level TBD from NOVICE
  analysis)
• MVIC will see a DDD of TBD MeV/g
• This is below the conservative PDR estimate
• This level is not normally a concern for CCD
  technology
• DDD parts assessment documented in BATC EEE Parts
  Radiation Effects Assessment (doc TBD)

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APL Status - SEE

• AD9240 is susceptible to SEL
• Worst day (CME or flare) SEL rate and mean time
  to latchup (MTTL) are
• 1.05E-1 SEL/device-day or MTTL 9.5 peak days
  (9.5 CME events)
• Average latchup rate and MTTL are
• 1.06E-4 SEL/device-day or MTTL26 years
• SEL will be a very rare event
• AD9240 is being repackaged by Maxwell
  Technologies along with a proven SEL
  detection/correction circuit
• Due to specific supply current threshold
  settings, the Maxwell 9240LP detects and recovers
  from 50 of SELs
• Other SELs are undetectable and require periodic
  power reset by control electronics this
  function is in the design
• All other parts including the oscillator hybrid
  are approved as latchup-immune based on direct
  test data or similar part/process test data or
  technology
• SEE assessment documented in BATC EEE Parts
  Radiation Effects Assessment (doc TBD)

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Subcontractor Radiation Design Status

• SWRI electronics design meets TID and DDD
  performance requirements (SWRI doc TBD)
• SWRI electronics design will perform in spite of
  the single particle environment (SWRI doc TBD)
• Design mitigates anticipated SEUs and SETs in
• Optocouplers and optoFETs
• Processor, FPGA and memory
• Data converters
• Logic
• Linears

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Outstanding Tasks

• OP490 ELDRS RLAT to be completed by 26 Sep 03
• High dose rate tests indicate tolerance to 10-15
  krad(Si)
• Probability of actual ELDRS response or bias
  sensitivity is low
• Fallback is refined 3-D shielding analysis plus
  spot shielding if necessary