space environment basics & calculation methods€¦ · galactic cosmic rays discovered in 1912...

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



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



Course Outline


2.Solar Particles





6.Calculation methods



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



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



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).



The Trapped Radiation EnvironmentInner Belt: South Atlantic Anomaly

UoSAT SEUs

After Daly



The Trapped Radiation EnvironmentInner Belt: SAA Solar Cycle variability

Solar Maximum

>92 MeV protons at 800 km>92 MeV protons at 500 km



The Trapped Radiation EnvironmentInner Belt: SAA Solar Cycle variability

Solar Minimum

>92 MeV protons at 800 km>92 MeV protons at 500 km



The Trapped Radiation EnvironmentInner Belt: SAA

Proba-V/EPT92 MeV Protons 0.5 MeV electrons



The Trapped Radiation EnvironmentOuter Belt: It’s Dynamic

Pro

tons

Ele

ctr

ons



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



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



The Trapped Radiation EnvironmentAP-8 Uncertainties/Accuracy



The Trapped Radiation EnvironmentAE-8 Uncertainties/Accuracy



Trapped Radiation EnvironmentTemporal Accuracy



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.



Trapped Radiation EnvironmentAnisotropy – Low Altitude



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



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



Course Outline


2.Solar Particles








Solar Particles

Solar Events of October – November 2003.Images from the SOHO and GOES spacecrafts

After Nieminen



Solar ParticleStochastic/Event Driven Environment

Modelled with “Confidence” based Models




Modelled with “Confidence” based Models,

e.g. “Log-Normal” Distribution, or max. entropy statistics



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



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



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



Course Outline


2.Solar Particles








After J. Barth, 1997 NSREC Short course

Galactic Cosmic RaysComposition



Galactic Cosmic RaysAnti-Correlation with Solar Cycle



Galactic Cosmic Raysvariation with location



Galactic Cosmic RaysGeomagnetic Shielding

ECSS Methods:

• Størmer’s Theory

• Magnetocosmics

• Smart & Shea

• L>5

• Ignore it, use

interplanetary

environment



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.



Course Outline


2.Solar Particles








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)




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.




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]




Heavy ion – matter interaction:

o Essentially same as with proton except

much higher energies involved



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



Course Outline


2.Solar Particles








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!



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.



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.



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.



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



TID - Examples of dose depth curves



TID - Dose-Depth Curve Components



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



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



SR-NIEL for IonsGa(1),As(1)[21 eV]

ONERA-NEMO GaAs



TNID - Displacement damage Curve (electron)



TNID - Displacement damage Curve (neutrons)



TNID - Examples of DDEF depth curves for various missions

dEENIELtEMeVNIEL

tMeV

)(),()10(

110

5 year @ LEO

15 year @ 1400 km

15 year @ GEO



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

be

.com

/wa

tch

?v=

lr2r6

6K

o2

60



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?



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



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


5.4 mm Al



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


5.4 mm Al



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)




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


5.4 mm Al

Shielded Energy



SEE - GCR LET spectra for different orbits (GCR ISO model)

GEO

LEO polar

ISS

Difference due to

Geomagnetic

Shielding



SEE - LET spectra, solar activity vs. solar event activity @ GEO orbit

Fluence Spectra

Flux Spectra



SEE - LET spectra, solar activity vs. solar event activity @GEO

Fluence Spectra

Flux Spectra

Zoom in of previous slideFlux

Fluence



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



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).



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



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



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



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



Examples of sector analysis



Example of sector analysis on Proba 3



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



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



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!



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

http://www.spenvis.oma.be/

http://trad.fr/OMERE-Software

http://www.swpc.noaa.gov/

http://virbo.org/

http://craterre.onecert.fr/ipsat

space environment basics & calculation methods€¦ · galactic cosmic rays discovered in 1912...

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