space environment basics & calculation methods€¦ · galactic cosmic rays discovered in 1912...
TRANSCRIPT
Space Environment Basics & Calculation methods
Presenter: Hugh Evans
TEC-EES
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Course Outline
1.The Earth’s Trapped Radiation Belts
2.Solar Particles
3.Galactic Cosmic Rays
4.Interactions of radiation particles with
electronic devices and materials
5.Top level space environment requirements
6.Calculation methods - Tools
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Solar event protons,
heavy ions, and electrons
Jovian
electrons
Solar flare
neutrons
and g-rays
Solar
X-rays
Galactic and extra-galactic
cosmic rays
Secondary
emissions
Neutrinos
Trapped
particles
Anomalous
cosmic rays
After Nieminen
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Course Outline
1.The Earth’s Trapped Radiation Belts
2.Solar Particles
3.Galactic Cosmic Rays
4.Interactions of radiation particles with
electronic devices and materials
5.Top level space environment requirements
6.Calculation methods
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation Environment
• Van Allen belts. Discovered during first space missions.
• Electrons and protons trapped in Earth Magnetic field (Lorentz force)
NASA, Radiation Belts Storm Probe mission
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentParticle Motion
Triple motion of a charged
particle in the radiation belts:
spiral motion (gyration),
bounce motion, and drift . 1 MeV e- 10 MeV p+
Gyration Radius
500 km 0.6 km 50 km
500 km 0.6 km 50 km
Gyration Period
500 km 10-5 s 7×10-3 s
20000 km 2×10-4 s 0.13 s
Bounce Period
500 km 0.1 s 0.65 s
20000 km 0.3 s 1.7 s
Longitudinal Drift
500 km 10 s 3 s
20000 km 3.5 s 1.1 s
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentSome Facts
Inner belt is dominated by a population of energetic protons up to ~400 MeV energy range
o Product of Cosmic-Ray Albedo Neutron Decay (CRAND)
o Inner edge is encountered as the South Atlantic Anomaly (SAA)
o Dominates the Space Station and LEO spacecraft environments
Outer Belt is dominated by a population of energetic electrons up to 7 MeV;
o Frequent injections and dropouts associated with storms and solar material interacting with magnetosphere
o Dominates the geostationary orbit environment and Navigation (Galileo, GPS) orbits, as well as certain missions in highly elliptic orbits (XMM-Newton, INTEGRAL, Proba 3).
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentInner Belt: South Atlantic Anomaly
UoSAT SEUs
After Daly
ESA Internal Course, EEE Component Radiation Hardness
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The Trapped Radiation EnvironmentInner Belt: SAA Solar Cycle variability
Solar Maximum
>92 MeV protons at 800 km>92 MeV protons at 500 km
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentInner Belt: SAA Solar Cycle variability
Solar Minimum
>92 MeV protons at 800 km>92 MeV protons at 500 km
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentInner Belt: SAA
Proba-V/EPT92 MeV Protons 0.5 MeV electrons
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentOuter Belt: It’s Dynamic
Pro
tons
Ele
ctr
ons
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentStandard Models
Trapped Protons (AP-8 model) - Trapped Electrons (AE-8 model)
• AE8 and AP8 are static average models giving proton and electron spectra at solar Minimum and solar Maximum at all geomagnetic coordinate points.
• For Earth orbits, AE-8 and AP-8 are ECSS standard models.For GEO and GPS orbits the IGE2006 and ONERA MEOv2, respectively may be used for trapped electrons instead
• Geomagnetic field model: Jensen-Cain 1960
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentStandard Models
• AE-8 and AP-8 are designed for long term degradation (TID and TNID/DDD), but work reasonably well for missions > 6 months.
• Drawbacks:
o Environment is dynamic, models are static therefore not suitable for short periods,
o no “real” solar cycle modulation (MAX/MIN models),
o geomagnetic field drift induces drift of SAA,
o Low altitude, low inclination orbits – not suitable
o no worst case model for trapped electrons
o Accuracy is at best factor of 2-3
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentAP-8 Uncertainties/Accuracy
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentAE-8 Uncertainties/Accuracy
ESA Internal Course, EEE Component Radiation Hardness
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Trapped Radiation EnvironmentTemporal Accuracy
ESA Internal Course, EEE Component Radiation Hardness
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Trapped Radiation EnvironmentJovian Radiation Belts
Very high Flux environment,
Very high energy electrons
(> 10 MeV)
But reasonably stable, i.e.
doesn’t appear as dynamic
as Earth’s belts. (NOT MUCH DATA, though)
Ganymede complicates
environment due to its own
magnetic field magnetic
shielding of Jovian belts
Io complicates environment
with regular volcanic ion
emmissions.
ESA Internal Course, EEE Component Radiation Hardness
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Trapped Radiation EnvironmentAnisotropy – Low Altitude
ESA Internal Course, EEE Component Radiation Hardness
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The Trapped Radiation EnvironmentNew developments – AE-9/AP-9
• New models developed AE-9/AP-9/SPM supported by NRO and
AFRL
o Allow to estimate the uncertainty in model fluxes due to
space weather effects and measurement uncertainty
o AX9 models: set of flux maps representing median, 95th
percentile of the distribution function of the particles and
contains Monte Carlo model to “simulate” space weather
dynamics etc…
o AX9 models range from plasma energy up to 10MeV for
electrons and 400MeV for protons
o AX9 models tend to predict more intense fluxes than AX8
• Not currently part of the ECSS standards
• Implemented in SPENVIS
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
The Trapped Radiation EnvironmentAx8 vs Ax9 Doses
Dose curves comparison between Ax8 and Ax9, generated with
Shieldose2, semi-infinite slab geometry.
After
S.
Husto
n e
t. a
l.
Ax-9 are complex models,
best practices for use are still under evaluation
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Course Outline
1.The Earth’s Trapped Radiation Belts
2.Solar Particles
3.Galactic Cosmic Rays
4.Interactions of radiation particles with
electronic devices and materials
5.Top level space environment requirements
6.Calculation methods
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Solar Particles
Solar Events of October – November 2003.Images from the SOHO and GOES spacecrafts
After Nieminen
ESA Internal Course, EEE Component Radiation Hardness
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Solar ParticleStochastic/Event Driven Environment
Modelled with “Confidence” based Models
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Solar ParticleStochastic/Event Driven Environment
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Solar ParticleStochastic/Event Driven Environment
Modelled with “Confidence” based Models,
e.g. “Log-Normal” Distribution, or max. entropy statistics
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Solar ParticlesConfidence Levels
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
1.E+07
1.E+08
1.E+09
1.E+10
1.E+11
1.E+12
1.E+13
0.1 1 10 100 1000
Tota
l Mis
sio
n F
lue
nce
[#/
cm²]
Energy [MeV]
Solar Proton Models
ESP 90%
JPL 90%
ESP/JPL
“confidence” does not
include accuracy of
underlying data set,
which can include a
significant error
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Solar ParticlesSTS-116 EVA
STS-116 mission to ISS
SPEs of December 2006 (GOES)
1E-02
1E-01
1E+00
1E+01
1E+02
1E+03
11/12 12:00 12/12 00:00 12/12 12:00 13/12 00:00 13/12 12:00 14/12 00:00 14/12 12:00 15/12 00:00 15/12 12:00 16/12 00:00
Flu
x (
1/c
m2
/sr/
s)
>10 MeV
>50 MeV
>100 MeV
STS-116 spacewalk 1
STS-116 spacewalk 2
After Nieminen
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Solar Particles
Radiation fluxes high for several days during solar events Solar flares are electrons rich, high 3He content relative to alpha
particles Coronal Mass Ejection is a large eruption of plasma (free ions and
electrons). CMEs responsible for major disturbances. Speeds vary from 50 to 2500km/s (12h to a few days to reach the Earth).
Energy spectrum highly variable Solar activity cycle approximately 11 years long Fluences high enough to cause damage => importance of proper
shielding Essentially unpredictable, however efforts dedicated to address the
problem in various Space Weather initiatives Models:
o CREME96 models for solar particles (protons and heavy ions) peak fluxes (Worst week, Worst Day and Peak 5min)
o ESP-PSYCHIC for worst-event and long term (7yr+) Solar particles are shielded by the Earth magnetic field ECSS standard models: ESP for solar particles fluences, CREME96
for solar particles peak flux models
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Course Outline
1.The Earth’s Trapped Radiation Belts
2.Solar Particles
3.Galactic Cosmic Rays
4.Interactions of radiation particles with
electronic devices and materials
5.Top level space environment requirements
6.Calculation methods
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
After J. Barth, 1997 NSREC Short course
Galactic Cosmic RaysComposition
ESA Internal Course, EEE Component Radiation Hardness
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Galactic Cosmic RaysAnti-Correlation with Solar Cycle
ESA Internal Course, EEE Component Radiation Hardness
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Galactic Cosmic Raysvariation with location
ESA Internal Course, EEE Component Radiation Hardness
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Galactic Cosmic RaysGeomagnetic Shielding
ECSS Methods:
• Størmer’s Theory
• Magnetocosmics
• Smart & Shea
• L>5
• Ignore it, use
interplanetary
environment
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Galactic Cosmic Rays
Discovered in 1912 by Austrian Victor Hess
Supernovae produce high energy cosmic rays, accelerated by moving shocks, as suggested by Enrico Fermi in 1949.
Charged particles accelerated to near speed of light (can reach ~1020 eV range. The most powerful particle accelerators on Earth “weak” in comparison, LHC ~1012 eV)
Flux ~ 4 particles /cm2/sec in space, anti-correlation with solar activity
Geomagnetic field offers some shielding
Atmosphere shields Earth’s surface from “primary" cosmic rays
Collisions in upper atmosphere produce "secondary" cosmic rays - some reach ground level (seen in “neutron monitors”)
Average person is crossed by ~ 100 relativistic muons per second
ECSS standard model for GCR fluxes is the ISO15390. CREME96 model is still widely used.
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Course Outline
1.The Earth’s Trapped Radiation Belts
2.Solar Particles
3.Galactic Cosmic Rays
4.Interactions of radiation particles with
electronic devices and materials
5.Top level space environment requirements
6.Calculation methods
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Interaction of Radiation Particles with Electronic Devices and Materials (1)
The effects of radiation on electronic devices and materials
depend on:
• Type of radiation (photon, electron, proton...)
• Rate of interaction
• Type of material (Silicon, GaAs..)
• Component characteristics (process, structure, etc.)
Consequences :
• Ionization (TID and SEE)
• Internal Charging (DDC)
• and Displacement Damage (TNID)
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Interaction of Radiation Particles with Electronic Devices and Materials (2)
Electron-matter interaction:o Non linear trajectoryo Bremsstrahlung productiono 1D shielding analysis with
Shieldose or Mulassiso Interactions best described
by Monte Carlo analysis (GEANT4)
Range in Al: R(cm) = 0.196E(MeV) – 0.04for 1 < E < 20 MeV
i.e. for E = 5MeV, R = 9cm
After Daly
0.00
0.01
0.10
1.00
10.00
100.00
1000.00
0.01 0.1 1 10 100 1000
CS
DA
Ra
ng
e (
mm
Al)
Energy (MeV)
Range in Al.
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Interaction of Radiation Particles with Electronic Devices and Materials (3)
Proton-matter interaction:
o Linear trajectory
o Energy loss via direct and
indirect ionization
o Spallation reactions for
E > 10 MeV
o Range in Al:
R(cm) = 10-3×E1.74 (MeV)
For E = 7MeV, R = 0.3mm
For E = 100MeV, R = 3cm
For E = 1GeV, R = 160cm
0.000001
0.00001
0.0001
0.001
0.01
0.1
1
10
100
1000
10000
0.001 0.01 0.1 1 10 100 1000 10000
Ra
ng
e [
cm
]
Energy (MeV)
ALUMINUM
CSDA Range[cm]
Projected Range[cm]
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Interaction of Radiation Particles with Electronic Devices and Materials (4)
Heavy ion – matter interaction:
o Essentially same as with proton except
much higher energies involved
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Interaction of Radiation with Electronic Devices and Materials (5)
1. Particles causing Single Events Effects:
o Galactic cosmic rays
o Solar particles
o Trapped protons in radiation belts
Note: protons are only significant for silicon components with
LETth < 15 MeV cm²/mg (usually…)
2. Particles causing long term degradation radiation damage:
o Trapped electrons in radiation belts (TID)
o Trapped protons in radiation belts (TID, Displacement
damage)
o Protons from solar flares
3. Particles causing Internal charging: Electrons
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Course Outline
1.The Earth’s Trapped Radiation Belts
2.Solar Particles
3.Galactic Cosmic Rays
4.Interactions of radiation particles with
electronic devices and materials
5.Top level space environment requirements
6.Calculation methods
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Defining the space radiation environment for EEE components
Orbit
Launch date & mission duration
Geomagnetic field model
Trapped particles fluxes (electrons and protons)
Solar particles peak fluxes and fluences
GCR fluxes
Total Ionising Dose depth curve (in Si and GaAs)
Total Non-Ionising Dose depth curve (in Si and GaAs)
NIEL curve(s)
LET spectra for nominal and solar flare conditions
Uncertainties in the models!
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Basic Radiation Effects:
• Total Ionising Dose (TID)
• Total Non-Ionising Dose (TNID)
(includes solar cell degradation)
• Internal Charging (DDC)
• Single Event Effects (SEE)
• Human effects (not covered)
Dose Eq., Effective dose, etc.
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
TID - Calculating received dose at part level
TID at part level is usually calculated by either using a dose
depth curve or 3D Monte Carlo analysis
Inputs for Monte Carlo calculations are particle fluxes and
mission duration
Inputs necessary to generate Total Ionizing Dose curves are
electron and protons fluxes (integral or differential)
SHIELDOSE-2 (from Seltzer) calculates electron and proton
doses for Al planar and spherical shields for various detectors
material (Si, GaAs…)
Dose depth curves can also be generated by MonteCarlo
(Geant4, Novice).
SHIELDOSE-2 implemented in SPENVIS and OMERE.
ESA Internal Course, EEE Component Radiation Hardness
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TID - Dose curves - Geometries
Spherical shell shielding used by Astrium for GEO telecom missions
Semi-Infinite Slab used for materials/coatings
Solid spherical shielding most commonly used.
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
TID - Dose curves geometries (GEO)
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
1.00E+08
1.00E+09
1.00E+10
0 10 20 30
Do
se (
rad
)
Aluminium thickness (mm)
Solid sphere
Shell sphere
Finite slab
Semi-infinite slab
• Only spherical dose curves shall be used for sector analysis
• Solid sphere –slant path
• Shell sphere –minimum path, but with care
ESA Internal Course, EEE Component Radiation Hardness
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TID - Examples of dose depth curves
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TID - Dose-Depth Curve Components
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TNID - Displacement damage calculation
Device degradation due to displacement damage can be
evaluated using the Non-Ionising Energy Loss (NIEL) curve
(MeV.cm2/mg)
With a NIEL curve for a given material (Si, GaAs…), calculate
Displacement Damage Equivalent Fluence (DDEF):
DDEF at part level can be either calculated by sector analysis or
MonteCarlo, as with TID
If NIEL curve not available in literature, can use either:
INFN Screened-Relativistic NIEL calculator (SPENVIS), or
ONERA NEMO (NIEL Evaluation Model of ONERA) (OMERE).
dEENIELtEMeVNIEL
tMeV
)(),()10(
110
ESA Internal Course, EEE Component Radiation Hardness
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TNID - Displacement damage Curve (proton)
1.E-03
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
0.0001 0.01 1 100 10000
Dam
ag
e (
MeV
.cm
2/g
)
Energy (MeV)
Non-Ionising Energy Loss: Protons (Silicon)
CERN/Rose
SPENVIS (JPL?)
Si (21eV) (Summers 1993)
Si (12.9 eV) (Summers 1993)
Dale (1994)
Akkermann -2001 (Si)
Huhtinen (1993)
Messenger 2003
SR-NIEL for Ions Si(1)[21 eV]
1.E-03
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
0.0001 0.01 1 100
Dam
ag
e (
MeV
.cm
2/g
)
Energy (MeV)
Non-Ionising Energy Loss: Protons (GaAs and InP)
GaAs (10, 6.7 eV)(Summers 1993)
Messenger GaAs (2003)
INFN-ESA-SR-2014-10eV
INFN-ESA-SR-2014-21eV
INFN-ESA-SR-2014-25eV
SR-NIEL for IonsGa(1),As(1)[21 eV]
ONERA-NEMO GaAs
ESA Internal Course, EEE Component Radiation Hardness
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TNID - Displacement damage Curve (electron)
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TNID - Displacement damage Curve (neutrons)
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TNID - Examples of DDEF depth curves for various missions
dEENIELtEMeVNIEL
tMeV
)(),()10(
110
5 year @ LEO
15 year @ 1400 km
15 year @ GEO
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
DDC – Electrons stopping in dielectrics
DDC – Deep Dielectric Charging
a.k.a. “Internal charging”
Caused by Energetic electrons stopping in a dielectric and unable to “move”. This results in an electric field build up which, with sufficient time, can exceed material breakdown voltage.
Results in transient currents flowing through cables when discharge occurs.
Radiation belt model:
FLUMIC: 99% worst dayLichtenberg figures
NU
TE
K C
orp
.
https://w
ww
.yo
utu
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.com
/wa
tch
?v=
lr2r6
6K
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60
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
SEE - LET spectrum
To study the effects of GCR in microcircuits, heavy ions are commonly described by amount of energy lost per unit track length: Linear Energy Transfer
Linear Energy Transfer (LET)
Energy loss per unit path length
dE/dx = MeV/cm
Divide by material density MeV-cm2/mg
LET of 97 MeV-cm2/mg corresponds to charge deposition of 1pC/mm
How does LET spectrum relate to the real space environment?
ESA Internal Course, EEE Component Radiation Hardness
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SEE - LET vs. Energy
0.1 1.0 10.0 100.0 1000.0 10000.0 100000.00
10
20
30
40
50
60
70
80
90
100
110
H
He
Li
Fe
Ni
Te
I
Au
Pb
U
Energy (MeV/u)
LE
T (
MeV
-cm
2/m
g)
After J. Barth, 1997 NSREC
Short course
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SEE - GCR Space Environment vs. LET
0.1 1.0 10.0 100.010-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
104
LET (MeV-cm2/mg)
Flu
ence
(#/c
m2)
Total
H
He
Li
Mg
Fe
Ni
I
Au
Pb
U
200 mils
After J. Barth, 1997 NSREC Short course
5.4 mm Al
ESA Internal Course, EEE Component Radiation Hardness
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SEE - SEP Space Environment vs. LET
0.1 1.0 10.0 100.010-13
10-12
10-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
LET (MeV-cm2/mg)
Flu
x (
#/c
m2/s
)
Total
H
He
Li
Mg
Fe
Ni
I
Au
Pb
U
After J. Barth, 1997 NSREC Short course
5.4 mm Al
ESA Internal Course, EEE Component Radiation Hardness
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SEE - LET and range vs. energy: Fe
10-2 10-1 100 101 102 103 104
Energy (MeV/u)
0
10
20
30
40
LE
T (
Me
Vcm
2/m
g)
100
101
102
103
104
105
106
ran
ge
(u
m)
After J. Barth, 1997 NSREC Short course
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SEE - Testing to the Environment - GCR
0.1 1.0 10.0 100.0let_all
10-15
10-14
10-13
10-12
10-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
f_al
l
for E > 0.1 MeV/n
for E > 25 MeV/n
for E > 200 MeV/n
LET (MeV-cm2/mg)
LE
T F
lux (
#/c
m2/d
ay)
Total Integral LET Spectra
After J. Barth, 1997 NSREC Short course
5.4 mm Al
Shielded Energy
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SEE - GCR LET spectra for different orbits (GCR ISO model)
GEO
LEO polar
ISS
Difference due to
Geomagnetic
Shielding
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SEE - LET spectra, solar activity vs. solar event activity @ GEO orbit
Fluence Spectra
Flux Spectra
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SEE - LET spectra, solar activity vs. solar event activity @GEO
Fluence Spectra
Flux Spectra
Zoom in of previous slideFlux
Fluence
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Course Outline
1. The Earth’s Trapped Radiation Belts
2. Solar Particles
3. Galactic Cosmic Rays
4. Interactions of radiation particles with electronic devices and materials
5. Top level space environment requirements
6. Calculation methods - Tools
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Predicting the radiation environment at component level
Several methods to calculate received Ionizing Dose or Non-ionizing dose at part level:
o 3D MonteCarlo. Can be either direct (GEANT4) or reverse (e.g. NOVICE) MonteCarlo. Huge computing time with GEANT4 but sometimes necessary for specialised instrumentation. NOVICE commonly used in industry, reasonable computing times (few hours per target). Requires proton and electron spectra as inputs. For displacement damage, NIEL curve in the appropriate target material also necessary.
o Sector analysis. Less accurate but quick (a few seconds per target) and often sufficient for EEE parts. Requires Total Ionizing dose curve or Total Non Ionizing dose curve as inputs
o The more complex the geometry of the CAD model, the higher the computing time.
Heavy ion and proton induced SEE rates calculated with SPENVIS and OMERE
o ECSS standard and CREME96 models available in both toolso Inputs necessary to calculate SEE rates are Integral LET spectrum
and device cross section. o Calculations performed only with simple spherical shielding
geometries (typically 1g/cm2).
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
TID, TNID computer methods for particle transport
After Daly, ESA report 1989
Compute charged particle
positional
orbit-averaged
mission-averaged
flux-vs-energy spectra
Simple-geometry
radiation transport
and dose computation
Complex-geometry
radiation transport
and dose computation
(Monte Carlo)
Solid-angle
sectoring
Dose at a point
Radiation
transport
data
Radiation
transport
data
Particle
environment
models
Vehicle
geometry
and material
specification
Dose-depth curve
Mission specification
Flux spectra Materials and
geometry specification
Geomagnetic
field models
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Sector Analysis - Definition
Based on “straight ahead” approximation
4π space around the detector is divided into
N elementary solid angles ωi
Calculate the dose di for each elementary
solid angle by using dose depth curve
Sum the contribution of all the sectors:
N
iiidD N1
4
1
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Ray tracing paths
Norm method Slant method
Norm method to be used in conjunction with Shell sphere dose curve
(Astrium GEO telecom spec only) and slant method with solid sphere
dose curve
r
r
rr
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Sector analysis
Simple or detailed sectoring analysis• Influence of material type is neglected. Different materials are
approximated to equivalent mass of a single material type (typically Al) by a proportional change in density.
• The sector shielding approach does not consider the physics involved in the performance of graded shields, dose enhancement, or in calculating the X-ray bremsstrahlung dose in a location shielded by tantalum
• Sectoring is not appropriate for the assessment of secondary hadron levels from materials with significantly different atomic mass number from the original target material.
• For electron dominated orbits (GEO, Navigation), sector/ray tracing analysis can overestimate or (sometimes) underestimate the dose levels.
• For proton dominated orbits (LEO), sector analysis give a good estimation of the dose level.
Example Sectoring Analysis tools• Fastrad• ESABase• SSAT
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Examples of sector analysis
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Example of sector analysis on Proba 3
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
TID at part level – ST5ST5 - Total Mission Dose on electronic parts
0
5
10
15
20
25
30
35
C&D
H_A
1
C&D
H_A
3
C&D
H_A
5
C&D
H_B
2
C&D
H_B
4
HPA_A
1
HPA_A
3
HPA_A
5
HPA_B
2
HPA_B
4
MSS
S_B1
MSS
S_C1
MSS
S_C3
MSS
S_C5
MAG
_ELE
C_2
MAG
_ELE
C_4
PRES
S_SENS
PSE_A
2
PSE_A
4
PSE_B
1
PSE_B
3
PSE_B
5
VEC_C
ON1_
2
VEC_C
ON1_
4
VEC_C
ON2_
1
VEC_C
ON2_
3
VEC_C
ON2_
5
XPOND_A
2
XPOND_A
4
XPOND_B
2
XPOND_B
4
XPOND_C
2
XPOND_C
4
Subsystem dose point
Mis
sio
n D
os
e (
kra
d(S
i))
An accurate spacecraft model
will increase the accuracy of
dose requirements
Top Level Requirement
200-35790km, 0 degree inclination, 3 months
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Monte Carlo Particle Transport
Detailed radiation “transport” calculations provide a more accurate treatment of the radiation interaction processes. Calculates:
o particle numbers, species, energy, and direction of propagation
MC required when accurate part level dose calculation necessary. MC Calculations based on the actual material employed MC calculations also include secondary particle information Example MC tools
o Geant4 based toolso NOVICEo MCNPX (limited accessibility)
Geant4 simulation of ISS ATV module
Ersmark (KTH) = DESIRE project
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
Conclusions
Defining the space radiation environment is an essential input to cope with radiation effects in EEE components during space missions.
Numerous future challenges:o Need for updated, more accurate and dynamic
models taking into account e.g. solar cycle activity variations (AE9/AP9 models)
o Better predictions of space weather is essential for future manned missions to the Moon and Mars.
o Improved transport models/codes would help produce more reliable and cost-effective spacecraft and facilitate the implementation of new space technologies
State the Errors in the Environment models impact on spacecraft Margin policies!
ESA Internal Course, EEE Component Radiation Hardness
Assurance Tutorial, ESTEC, 4 November 2016
References
1. IEEE NSREC Short courses
2. RADECS Short courses
3. ECSS-E-ST-10-04C
4. ECSS-E-ST-10-12C
5. The near-Earth Space Radiation Environment, S. Bourdarie et.
al., IEEE Trans. Nucl. Sci., Vol. 55, No. 4, Aug. 2008
6. www.spenvis.oma.be
7. http://trad.fr/OMERE-Software
8. www.swpc.noaa.gov
9. http://virbo.org
10.http://craterre.onecert.fr/ipsat