Military and Aerospace Applications of Programmable Devices and Technologies Conference Radiation Environments

1
Military and Aerospace Applications
ofProgrammable Devices and Technologies
ConferenceRadiation Environments

• Janet Barth
• NASA/Goddard Space Flight Center

Greenbelt, Maryland September 1998
2
The Radiation Environment
Galactic Cosmic Rays
Solar Protons Heavy Ions
Trapped Particles
Nikkei Science, Inc. of Japan, by K. Endo
3
Components of the Natural Environment

• Transient
• Galactic Cosmic Rays
• Hydrogen Heavier Ions
• Solar Particle Events
• Protons Heavier Ions
• Trapped
• Electrons, Protons, Heavier Ions
• Atmospheric Terrestrial Secondaries
• Neutrons

4
Effects

• Total Ionizing Dose
• Trapped Protons Electrons
• Solar Protons
• Single Event Effects
• Protons
• Trapped
• Solar
• Heavier Ions
• Galactic Cosmic Rays
• Solar Events
• Neutrons

• Displacement Damage
• Protons
• Electrons

5
Outline

• The Sun
• Transient Particles
• Galactic Cosmic Rays
• Solar Particle Events
• Trapped Particles
• Atmospheric Terrestrial Particles
• Nuclear Weapons Environment
• Summary

6
SunDominates the Environment
7
Solar Wind

• Stream of Charged Particles from Suns Corona
• Electrons
• Protons
• Heavy Ions
• Magnetized Plasma
• Detected Out to 10 billion km from Earth by
  Pioneer 10
• Velocity 300 - 900 km/s
• Energy .5 - 2.0 keV/nuc

?
Density 1 - 30 / cm3
8
Gradual Events

• Coronal Mass Ejections
• Particles Accelerated by Shock Wave
• Largest Proton Events
• Decay of X-Ray Emission Occurs Over Several Hours
• Large Distribution in Solar Longitude

Holloman AFB/SOON
9
Impulsive Events

• Solar Flares
• Particles Accelerated Directly
• Heavy Ion Rich
• Sharp Peak in X-Ray Emission
• Concentrated Solar Longitude Distribution

10
Sunspot Cycle
after Lund Observatory
Cycle 22
Cycle 21
Cycle 20
Cycle 19
Cycle 18
Sunspot Numbers
Years
Length Varies from 9 - 13 Years 7 Years Solar
Maximum, 4 Years Solar Minimum
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Sunspot Cycle with Magnetic Storms
Sunspots Magnetic Storm Days
Sunspot Number
of Days with Ap gt 4
Annual Sunspot Number
Annual Number of Days with Apgt4
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Galactic Cosmic Ray Ions

• All Elements in Periodic Table
• Energies in GeV
• Found Everywhere in Interplanetary Space
• Omnidirectional
• Mostly Fully Ionized
• Cyclic Variation in Fluence Levels
• Lowest Levels Solar Maximum Peak
• Highest Levels Lowest Point in Solar Minimum
• Single Event Effects Hazard
• Model CREME96

13
GCRs Nuclear Composition
Energy 2 GeV/n, Normalized to Silicon 106
H
He
C
O
Si
Fe
Relative Flux (Si 106)
Zr
Pt
Ba
Pb
Individual Elements
Even-Z Elements
Elemental Groups
Nuclear Charge (Z)
14
GCRs Solar Modulation
CNO - 24 Hour Averaged Mean Exposure Flux
Energy 25-250 MeV/n
IMP-8
CNO (/cm2/ster/s/MeV/n)
Date
15
GCRs Shielded Fluences - Fe
Interplanetary, CREME 96, Solar Minimum
Particles (/cm2/day/MeV/n)
Energy (MeV/n)
16
Magnetic Rigidity
Total Energy Required to Penetrate the
Magnetosphere
H
48 MeV
87 MeV
173 MeV
284 MeV
987 MeV
Magnetic Equator
2900 MeV
1147 MeV/n
313 MeV/n
109 MeV/n
46 MeV/n
23 MeV/n
12 MeV/n
Z gt 1
after Stassinopoulos
17
GCRs Shielded Fluences - Fe
CREME 96, Solar Minimum, 100 mils (2.54 mm) Al
Particles (/cm2/day/MeV/nuc)
Energy (MeV/nuc)
18
GCRs Integral LET Spectra
CREME 96, Solar Minimum, 100 mils (2.54 mm) Al
Z 2 - 92
LET Fluence (/cm2/day)
LET (MeV-cm2/mg)
19
Solar Particle Events

• Increased Levels of Protons Heavier Ions
• Energies
• Protons - 100s of MeV
• Heavier Ions - 100s of GeV
• Abundances Dependent on Radial Distance from Sun
• Partially Ionized - Greater Ability to Penetrate
  Magnetosphere
• Number Intensity of Events Increases
  Dramatically During Solar Maximum
• Models
• Dose - SOLPRO, JPL, Xapsos/NRL
• Single Event Effects - CREME96 (Protons Heavier
  Ions)

20
Sunspot Cycle with Solar Proton Events
Proton Event Fluences
Protons (/cm2)
Year
21
Solar Proton Event - October 1989
Protons Electrons - Magnetic Field 99 Worst
Case Event
Counts/cm2/s/ster/MeV
nT
GOES Space Environment Monitor
22
Proton Event Spectra - Cycle 22
Total Integral Proton Fluence
Proton Fluence (/cm2/event)
Energy (gt MeV)
23
TIROS Measurement of Protons
November 7, 1997 Coronal Mass Ejection
H 870/870 km
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TIROS Measurement of Protons
Day After Coronal Mass Ejection
H 870/870 km
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Solar Protons Orbits
Proton Levels Predicted by CREME 96
Averaged Over Worst Day
Protons (/cm2/sec/MeV)
Energy (MeV)
26
Effect of Shielding on Heavy Ions
Transient Particles Unattenuated by the
Magnetosphere
CREME96
Fluence (/cm2/s)
LET (MeV-cm2/mg)
27
SEU Rate Increases During Solar Events
Observation from UoSat-2 Meteosat-3 EDAC was
able to handle increased rates.
28
Trapped Radiation
Trapped Particles
Protons, Electrons, Heavy Ions
Nikkei Science, Inc. of Japan, by K. Endo
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Van Allen Belts
Outer Zone
Inner Zone
Heavy Ions
SAMPEX/NASA
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Trapped - Van Allen Belts

• Omnidirectional
• Components
• Protons E .04 - 500 MeV
• Electrons E .04 - 7(?) MeV
• Heavier Ions Low E - Non-problem for
  Electronics
• Location of Peak Levels Depends on Energy
• Average Counts Vary Slowly with the Solar Cycle
• Location of Populations Shifts with Time
• Counts Can Increase by Orders of Magnitude During
  Magnetic Storms
• March 1991 Storm - Increases Were Long Term

31
Trapped Particle Models

• NASA AP-8 AE-8
• Air Force CRRES APEX Models
• CRRESPRO, CRRESELE, CRRESRAD APEXRAD
• New Models - NASA Space Environment and Effects
  Program
• Low Altitude Model - lt 1000 km
• Boeing
• Based on TIROS Data
• Extended to Higher Altitudes
• Will Combine CRRES and TIROS Data

32
TIROS/NOAA Trapped Protons
Solar Cycle Variation 80-215 MeV Protons
B/Bmin1.0
L1.20
L1.18
L1.16
Proton Flux (/cm2/s)
Radio Flux F 10.7
L1.14
Date
Huston et al.
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Magnetic Storms - Hipparcos
Star Mapper - Radiation Background
L-Shell
4-Day, 9-Orbit Averages
Daly, et al.
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CRRES - Measured Proton Belt
AF Phillips Laboratory, SPD/GD
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Trapped Protons - 800 km
Protons E gt 30 MeV, Solar Max
Protons/cm2/sec
Latitude (deg)
Longitude (deg)
36
Trapped Electrons - 1000 km
Integral Electron Flux Contours E gt .5 MeV
37
SRAM Upset Rates on CRUX/APEX
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AP8 - MAX Spectra
Integral Proton Fluences

• Energy Range
• .04 - 500 MeV
• Range in Al
• 30 MeV .17 inch
• Effects
• Total Dose
• Single Event Effects
• Solar Cell Damage

Fluence (/cm2/day)
Energy (gtMeV)
39
Trapped Proton Predictions
I90 deg, H1000/1000 km, Solar Minimum
Protons (/cm2/s)
Energy (gt MeV)
40
AE-8 - MAX Spectra
Integral Electron Fluences

• Energy Range
• .04 - 7 MeV
• Range in Al
• Effects
• Total Dose
• Surface Charging
• Deep Dielectric Charging
• Solar Cell Damage

Fluence (/cm2/day)
Energy (gtMeV)
41
Interactions in the Atmosphere
IBM Journal of Research Development Terrestrial
Cosmic Rays and Soft Errors
42
Neutrons Pions

• Source - Secondary Products of Particle Cascades
• Spacecraft Materials
• Galactic Comic Ray Collisions with Atmospheric O
  N
• Single Event Upset Hazard
• Ground Level in Large Memory Banks
• Avionics
• Low Earth Orbits - Shuttle
• First Recognized as Problem in 1980s
• Models
• Atmospheric - Boeing Wilson-Nealy
• Ground - Empirical

43
Neutron Environment
Normand et al.
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1,000,000 feet 330 km
Shuttle
? Primary Cosmic Rays ?
Neutrons ?????Secondary Cosmic Rays
150,000 feet 50,000 m
Top of Atmosphere
Peak Neutron Flux
60,000 feet 20,000 m
?
35,000 feet 10,000 m
N,O
Aircraft
?
???
Ground 1/500 of Peak Flux
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Neutron Models Flux vs. Altitude
1-10 MeV Atmospheric Neutron Flux
1-10 MeV Neutron Flux (n/cm2/s)
Altitude ( Thousands of feet)
45
Neutron Model Flux vs. Latitude
1-10 MeV Atmospheric Neutron Flux
1-10 MeV Neutron Flux (n/cm2/s)
Averaged Over Longitude
Latitude (deg N)
46
Neutron Model Flux vs. Energy
Differential Neutron Flux - Atmospheric
Differential Flux (n/cm2/s/MeV)
Energy (MeV)
47
Terrestrial Cosmic Rays
48
Altitude Dependence of Terrestrial Effects
Repairs of Memory Modules
Normalized Number of Failures
From IBM Data Systems/1984
49
Nuclear Weapons Effects

• G. Welles Still
• Army Research Laboratory

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Nuclear Weapons Environment
gt 1014 n/s
gt 108 rads(si)/s
51
System Vulnerability to NWE

• Threat Effect Level of Effect
• Thermal Damage or destroy System
• mechanical and electrical
• integrity of system cables
• and enclosure.
• Blast Damage or destroy System
• Mechanical and electrical
• integrity of of system cables
• and enclosure.
• EMP Transient disturbances and Piece Part
• potential catastrophic and Circuit
• destruction through coupling
• of electric fields
• INR Shifts in performance Piece Part
• of individual components and Circuit

Initial Nuclear Radiation
52
Sample INR Survivability Criteria

• Tissue Absorption Total Dose 2500 rad(tissue)
• Max Gamma Contribution 1750 rad (tissue)
• Max Neutron Contribution 1500 rad (tissue)
• Silicon Absorption
• Max Combined 3000 rad (si)
• Neutron/Gamma Ionizing Dose
• Peak Gamma Dose Rate 2 x 109 rad (si)/s

53
Atmospheric Explosions

• Decay Products of Blast Become Trapped in Van
  Allen Belts
• Long Term Enhancement of Radiation Levels
• US - Starfish Explosion - July 9, 1962
• 10 Known Satellites Lost Due to Radiation Damage
• Inner Van Allen Fluxes Increased x 100 Due
  Fission Spectrum Electrons
• Dominated Inner Belt Levels for 5 Years
• Detectable for up to 8 Years

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Solar Cycle Effects

• Solar Maximum
• Trapped Proton Levels Lower
• GCR Levels Lower
• Solar Events More Frequent Greater Intensity
• Solar Minimum
• Trapped Protons Higher
• GCR Levels Higher
• Solar Events Are Rare

55
Models of the Environment

• Trapped Particles
• NASA AP-8 AE-8 - Data from 1960s 1970s
• AFRL CRRESPRO CRRESELE - Solar Max Only
• MDAC - Low Altitude Improvements for Protons
  Based on NOAA/TIROS Data
• Galactic Cosmic Ray Heavy Ions
• CREME96 - Update to Outdated CREME86
• Solar Protons Heavier Ions
• Solar Proton Model - Total Fluence Peak
  Particles
• CREME96 - Update to Inadequate CREME86

Supported by NASA/Space Environment Effects
Program
56
Environment Definition

• Total Ionizing Dose
• Dose-Depth Curves or Spacecraft Specific Dose
  Levels
• Trapped Protons Electrons
• Solar Protons
• Secondary Bremsstrahlung (High Electron
  Environments)
• Single Event Effects - Average Peak Conditions
• Galactic Cosmic Ray Heavy Ions (LET Spectra)
• Solar Heavy Ions (LET Spectra)
• Solar Protons (Energy Spectra)
• Trapped Protons (Energy Spectra)