Space Radiation and its Effects on EEE Components

space.epfl.ch

Space Radiation and its Effects on EEE Components

ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Marc Poizat

ESA/ESTEC

TEC-QEC

ong>Spaceong> Environment ong>andong>

ong>Effectsong>

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Course Outline

• The Earth’s Trapped ong>Radiationong> Belts

• Solar Particles

• Galactic Cosmic Rays

• Interactions of radiation particles with

electronic devices ong>andong> materials

• Top level space environment requirements

• Calculation methods

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Galactic ong>andong> extra-galactic

cosmic rays

Neutrinos

EPFL ong>Spaceong> Center 9th June 2009

Solar

X-rays

Solar flare

neutrons

ong>andong> γ-rays

Secondary

emissions

Anomalous

cosmic rays

Trapped

particles

Jovian

electrons

Solar event protons,

heavy ions, ong>andong> electrons


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The magnetosphere : a natural shield

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Course Outline

• The Earth’s Trapped ong>Radiationong> Belts

• Solar Particles

• Galactic Cosmic Rays

• Interactions of radiation particles with

electronic devices ong>andong> materials

• Top level space environment requirements

• Calculation methods

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The trapped radiation belts

• Van Allen belts. Discovered during first space missions.

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The trapped radiation belts = dynamic environment

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The Trapped ong>Radiationong> Environment (1)

• Inner belt is dominated by a population of energetic protons up

to ~400 MeV energy range

– Product of Cosmic-Ray Neutron Decay

– Inner edge is encountered as the South Atlantic Anomaly

(SAA)

– Dominates the ong>Spaceong> Station ong>andong> LEO spacecraft

environments

• Outer Belt is dominated by a population of energetic electrons

up to 7 MeV;

– Frequent injections ong>andong> dropouts associated with storms

ong>andong> solar material interacting with magnetosphere

– Dominates the geostationary orbit environment (mostly

telecom) ong>andong> Navigation (Galileo, GPS) orbong>itsong>, as well as

certain Science missions in highly elliptic orbong>itsong> (XMM-

Newton, INTEGRAL)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The Trapped ong>Radiationong> Environment (2)

• Trapped Electrons (AE8 model) - Trapped Protons (AP8 model)

• AE8 ong>andong> AP8 are static models giving proton ong>andong> electron spectra at solar

Minimum ong>andong> solar Maximum at all geomagnetic coordinate points.

• But environment dynamic

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The Trapped ong>Radiationong> Environment (3)

• Motion of a charged particle in the radiation belts: triple

motion.

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The Trapped ong>Radiationong> Environment (4)

• The South Atlantic Anomaly

EPFL ong>Spaceong> Center 9th June 2009

UoSAT SEUs


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The Trapped ong>Radiationong> Environment (5)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The Trapped ong>Radiationong> Environment (6)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

The Trapped ong>Radiationong> Environment (7)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Course Outline

• The Earth’s Trapped ong>Radiationong> Belts

• Solar Particles

• Galactic Cosmic Rays

• Interactions of radiation particles with

electronic devices ong>andong> materials

• Top level space environment requirements

• Calculation methods

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Solar Particles (1)

� Solar Events of October – November 2003.

Images from the SOHO ong>andong> GOES spacecrafts

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Solar Particles (2)

ong>Radiationong> fluxes high for several days during solar flares

� Solar activity cycle approximately 11 years long

� Fluences high enough to cause damage => importance

of proper shielding

� Include protons ong>andong> heavy ions

� Energy spectrum highly variable

� Essentially unpredictable, however efforts dedicated to

address the problem in various ong>Spaceong> Weather initiatives

� Analysis methods are statistical (e.g. ESP, JPL-91,

models, available in SPENVIS, OMERE)

� Solar particles are shielded by the Earth magnetic field

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Solar Particles (3)

• STS-116 mission to ISS

EPFL ong>Spaceong> Center 9th June 2009

Flux (1/cm2/sr/s)

1E+03

1E+02

1E+01

1E+00

1E-01

1E-02

SPEs of December 2006 (GOES)

>10 MeV

>50 MeV

>100 MeV

STS-116 spacewalk 1

STS-116 spacewalk 2

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


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Course Outline

• The Earth’s Trapped ong>Radiationong> Belts

• Solar Particles

• Galactic Cosmic Rays

• Interactions of radiation particles with

electronic devices ong>andong> materials

• Top level space environment requirements

• Calculation methods

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Galactic Cosmic Rays (1)

� Flux ~ 4 particles /cm 2 /sec in space, anticorrelation with solar activity

� 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

� 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 ~10 20 eV range. The most powerful particle accelerators

on Earth “weak” in comparison)

� Most accurate GCR model is CREME96 by NRL.

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Galactic Cosmic Rays (2)

• Anticorrelation with solar min/max periods

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

• Composition

Galactic Cosmic Rays (3)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Course Outline

• The Earth’s Trapped ong>Radiationong> Belts

• Solar Particles

• Galactic Cosmic Rays

• Interactions of radiation particles with

electronic devices ong>andong> materials

• Top level space environment requirements

• Calculation methods

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Interaction of ong>Radiationong> Particles with

Electronic Devices ong>andong> Materials (1)

The effects of radiation on electronic devices ong>andong> materials

depend on :

• Type of radiation (photon, electron, proton...)

• Rate of interaction

• Type of material (Silicon, GaAs..)

• Component related (process, structure, etc.)

Consequences : Ionization (TID ong>andong> SEE) ong>andong>

Displacement Damage

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Interaction of ong>Radiationong> Particles with

Electronic Devices ong>andong> Materials (2)

• Electron-matter interaction:

– Non linear trajectory

– Bremsstrahlung production

– 1D shielding analysis with

Shieldose or Mulassis

– Interactions best described

by Monte Carlo analysis (GEANT4)

– Range in Al:

• R(cm) = 0.196E (MeV) – 0.04

(for 1 < E < 20 MeV i.e. for E = 5MeV, R = 9cm)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Interaction of ong>Radiationong> Particles with

Electronic Devices ong>andong> Materials (3)

• Proton-matter interaction:

– Linear trajectory

– Energy loss via direct ong>andong> indirect ionization

– Spallation reactions for E > 10 MeV

– Range in Al: R(cm) = 10 -3 .E 1.74 (MeV)

For E = 7MeV, R = 0.3mm

For E = 100MeV, R = 3cm

For E = 1GeV, R = 160cm

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Interaction of ong>Radiationong> Particles with

Electronic Devices ong>andong> Materials (4)

• Heavy ion – matter interaction:

– Essentially same as with proton except much higher

energies involved

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Interaction of ong>Radiationong> with Electronic

Devices ong>andong> Materials (5)

• Particles causing Single Events ong>Effectsong>

– Galactic cosmic rays

– Cosmic solar particles (heavily influenced by solar flares)

– Trapped protons in radiation belts

• Particles causing long term degradation radiation damage

– Trapped electrons in radiation belts (TID)

– Trapped protons in radiation belts (TID, Displacement damage)

– Protons from solar flares

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Course Outline

• The Earth’s Trapped ong>Radiationong> Belts

• Solar Particles

• Galactic Cosmic Rays

• Interactions of radiation particles with

electronic devices ong>andong> materials

• Top level space environment requirements

• Calculation methods

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Calculating total ionizing dose

• SHIELDOSE2 (from Seltzer) calculates electron ong>andong> proton doses

for Al planar ong>andong> spherical shields for various detectors material (Si,

AsGa…)

• Can be generated by MonteCarlo.

• Inputs necessary to generate Total Ionizing Dose curves are

electron ong>andong> protons fluxes (integral or differential)

• SHIELDOSE implemented in SPENVIS ong>andong> OMERE.

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Sector Analysis - Geometries

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Dose depth curve for a 5 year LEO polar mission

(800km, 98deg)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Dose rate along LEO polar orbit

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Dose depth curve for a 15 year Navigation (Galileo, GPS)

mission (23000km, 56deg)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Dose depth curve for an 18 year geostationary mission

(36000km, 0deg, 160W)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Displacement damage calculation

• Device degradation due to displacement damage can be

evaluated thanks to NIEL (MeV.cm2/mg)

• If NIEL curve for a given material is known (Si, GaAs…), calculate

Displacement Damage Equivalent Fluence (DDEF):

Φ

10

1

=


NIEL(

10MeV

)

MeV ∫

• DDEF at part level can be either calculated by sector analysis or

MonteCarlo

• If NIEL curve not available in litterature, possibility if using NEMO

(NIEL Evaluation Model of ONERA). NEMO is a Geant4 based

tool implemented in OMERE.

EPFL ong>Spaceong> Center 9th June 2009

Φ(

E)

⋅NIEL(

E)


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

DDEF depth curve for a 5 year LEO mission

(800km, 98deg)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

DDEF depth curve for a 15 year Navigation (Galileo, GPS)

mission (23000km, 56deg)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

DDEF depth curve for an 18 year geostationary mission

(36000km, 0deg, 160W)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

LET spectrum

• To study the effects of GCR in microcircuong>itsong>,

heavy ions are commonly described by amount of

energy lost per unit track length i.e. Linear Energy

Transfer

• Linear Energy Transfer (LET)

– Energy loss per unit path length

– dE/dx = MeV/cm

– Divide by material density = MeV-cm 2 /mg

– LET of 97 MeV-cm 2 /mg corresponds to charge

deposition of 1pC/μm

• How does LET spectrum relate to the real space

environment?

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

LET (MeV-cm 2 /mg)

110

100

90

80

70

60

50

40

30

20

10

LET vs. Energy

0

0.1 1.0 10.0 100.0 1000.0 10000.0 100000.0

Energy (MeV/u)

EPFL ong>Spaceong> Center 9th June 2009

H

He

Li

Fe

Ni

Te

I

Au

Pb

U

After J. Barth, 1997 NSREC Short course


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Fluence (#/cm 2 )

GCR ong>Spaceong> Environment vs. LET

10 4

10 3

10 2

10 1

10 0

10 -1

10 -2

10 -3

10 -4

10 -5

10 -6

10 -7

10 -8

200 mils

10

0.1 1.0 10.0 100.0

-9

LET (MeV-cm 2 /mg)

EPFL ong>Spaceong> Center 9th June 2009

Total

H

He

Li

Mg

Fe

Ni

I

Au

Pb

U

After J. Barth, 1997 NSREC Short course


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Fluence (#/cm 2 /s)

SPE ong>Spaceong> Environment vs. LET

10 3

10 2

10 1

10 0

10 -1

10 -2

10 -3

10 -4

10 -5

10 -6

10 -7

10 -8

10 -9

10 -10

10 -11

10 -12

200 mils

10

0.1 1.0 10.0 100.0

-13

EPFL ong>Spaceong> Center 9th June 2009

LET (MeV-cm 2 /mg)

Total

H

He

Li

Mg

Fe

Ni

I

Au

Pb

U

After J. Barth, 1997 NSREC Short course


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Fe/cm 2 /s/MeV/n

ong>Spaceong> ong>Radiationong> Environment - Fe

10 3

10 2

10 1

10 0

10 -1

10 -2

10 -3

10 -4

10 -5

10 -6

10 -7

10 -8

10 -9

10 -10

10 -11

0.1 1.0 10.0 100.0 1000.0 10000.0 100000.0

30

0

0.1 1.0 10.0 100.0 1000.0 10000.0 100000.0

Energy (MeV/u)

EPFL ong>Spaceong> Center 9th June 2009

GCR

Solar peak Peak

LET

20

10

LET (MeV-cm 2 /mg)

After J. Barth, 1997 NSREC Short course


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

LET ong>andong> range vs. energy: Fe

LET (MeVcm 2 /mg)

40

30

20

10

0

10 -2

10 -1

10 0

10 1

Energy (MeV/u)

EPFL ong>Spaceong> Center 9th June 2009

10 2

10 3

10 4

10 6

10 5

10 4

10 3

10 2

10 1

10 0

After J. Barth, 1997 NSREC Short course

range (um)


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Pb/cm 2 /s/MeV/u

ong>Spaceong> ong>Radiationong> Environment - Pb

10 -3

10 -4

10 -5

10 -6

10 -7

10 -8

10 -9

10 -10

10 -11

10 -12

10 -13

10 -14

10 -15

10 -16

10 -17

0.1 1.0 10.0 100.0 1000.0 10000.0 100000.0

100

0

0.1 1.0 10.0 100.0 1000.0 10000.0 100000.0

Energy (MeV/u)

EPFL ong>Spaceong> Center 9th June 2009

GCR

Solar Peak

LET

90

80

70

60

50

40

30

20

10

de_dx

LET (MeV-cm 2 /mg)

After J. Barth, 1997 NSREC Short course


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Testing to the Environment - GCR

LET Fluence (#/cm 2 /day)

f_all

10 -1

10 -2

10 -3

10 -4

10 -5

10 -6

10 -7

10 -8

10 -9

10 -10

10 -11

10 -12

10 -13

10 -14

200 mils

Total Integral LET Spectra

10

0.1 1.0 10.0 100.0

let_all

-15

EPFL ong>Spaceong> Center 9th June 2009

LET (MeV-cm 2 /mg)

for E > 0.1 MeV/n

for E > 25 M eV/n

for E > 200 MeV/n

After J. Barth, 1997 NSREC Short course


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Testing to the Environment - Solar

LET Fluence (#/cm 2 /s)

f_all

10 3

10 2

10 1

10 -1

10 0

10 -2

10 -3

10 -4

10 -5

10 -6

10 -10

10 -9

10 -8

10 -7

10 -11

10 -12

10 -13

10 -14

200 mils

Total Integral LET Spectra

10

0.1 1.0 10.0 100.0

e_all

-15

EPFL ong>Spaceong> Center 9th June 2009

LET (MeV-cm 2 /mg)

for E > 0.1 MeV/n

for E > 25 MeV /n

for E >200 M eV /n

After J. Barth, 1997 NSREC Short course


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Fluence (#/cm 2 /s)

10 6

10 5

10 4

10 3

10 2

10 1

10 0

10 -1

10 -2

10 -3

10 -4

10 -5

10 -6

10 -7

10 -8

10 -9

10 -10

Direct Ionization by Protons

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00

0.6

GCR Surface

GCR 200 mils

GCR 500 mils

Solar Peak Surface

Solar Peak 200 mils

Solar Peak 500 mils

0.5

LET E >0.1 MeV

LET E > .01 MeV 0.4

0.0

0.01 0.10 1.00 10.00 100.00 1000.00 10000.00 100000.00

Energy (MeV)

EPFL ong>Spaceong> Center 9th June 2009

0.3

0.2

0.1

let_reg2

LET (MeV-cm 2 -mg)

After J. Barth, 1997 NSREC Short course


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

LET Fluence (#/cm 2 /s)

f_reg

10 -5

10 -4

10 -3

10 -2

10 -1

10 0

10 1

10 2

10 3

10 4

10 5

10 6

Low LET Protons

Total Integral LET Spectra

10

0.001 0.010 0.100

let_reg

1.000 10.000 100.000

-14

10 -13

10 -12

10 -11

10 -10

10 -9

10 -8

10 -7

10 -6

200 mils

EPFL ong>Spaceong> Center 9th June 2009

LET (MeV-cm 2 /mg)

GCR

Solar Peak

GCR

Solar Peak

After J. Barth, 1997 NSREC Short course


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Course Outline

• The Earth’s Trapped ong>Radiationong> Belts

• Solar Particles

• Galactic Cosmic Rays

• Interactions of radiation particles with

electronic devices ong>andong> materials

• Top level space environment requirements

• Calculation methods - Tools

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Predicting the radiation environment at

component level

• Several methods to calculate received Ionizing Dose or Non-ionizing

dose at part level:

– 3D MonteCarlo. Can be either direct (GEANT4) or reverse (e.g. NOVICE)

MonteCarlo. Huge computing time with GEANT4 (up to several months).

Requires proton ong>andong> electron spectra as inputs. For displacement damage,

NIEL curve in the appropriate target material also necessary.

– Sector analysis. Less accurate but quick ong>andong> often sufficient for EEE parts.

Requires Total Ionizing dose curve or Total Non Ionizing dose curve as inputs

– The more complex the geometry of the CAD model, the higher the computing

time.

• Heavy ion ong>andong> proton induced SEE rates calculated with CRÈME96

(creme96.nrl.navy.mil/).

CREME86 available in OMERE ong>andong> SPENVIS

– Inputs necessary to calculate SEE rates are Intergral LET spectrum ong>andong>

device cross section.

– Calculations performed only with simple shielding geometries

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

TID, TNID computer methods for particle

transport

Vehicle

geometry

ong>andong> material

specification

ong>Radiationong>

transport

data

Mission specification

Compute charged particle

positional

orbit-averaged

mission-averaged

flux-vs-energy spectra

Flux spectra

Simple-geometry

radiation transport

ong>andong> dose computation

Dose-depth curve

Solid-angle

sectoring

Dose at a point

EPFL ong>Spaceong> Center 9th June 2009

Particle

environment

models

Materials ong>andong>

geometry specification

Complex-geometry

radiation transport

ong>andong> dose computation

(Monte Carlo)

Geomagnetic

field models

ong>Radiationong>

transport

data

After Daly, ESA report 1989


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Sector Analysis - Definition

• Based on “straight ahead” approximation

• 4π space around the detector is divided into

N elementary solid angles ω i

• Calculate the dose d i for each elementary

solid angle by using dose depth curve

• Sum the contribution of all the sectors:

N 1

D = 4π

N


i=

1

EPFL ong>Spaceong> Center 9th June 2009


d

i


ωi


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Ray tracing paths

• Norm method Slant method

r

r

• Norm method to be used in conjunction

with Shell sphere dose curve ong>andong> slant

method with solid sphere dose curve

EPFL ong>Spaceong> Center 9th June 2009

r

r

α


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

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 orbong>itsong> (GEO, Navigation), sector/ray tracing analysis can

overestimate or (sometimes) underestimate the dose levels.

– For proton dominated orbong>itsong> (LEO), sector analysis give a good estimation of the dose level.

• Example Sectoring Analysis tools

– Fastrad

– ESABase

– SSAT (capable of implementing Geant4 geometry)

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Examples of sector analysis tools

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Mission Dose (krad(Si))

35

30

25

20

15

10

5

0

TID at part level – ST5

200-35790km, 0 degree inclination, 3 months

C&DH_A1

C&DH_A3

C&DH_A5

C&DH_B2

C&DH_B4

HPA_A1

HPA_A3

HPA_A5

HPA_B2

HPA_B4

MSSS_B1

MSSS_C1

MSSS_C3

MSSS_C5

MAG_ELEC_2

MAG_ELEC_4

PRESS_SENS

PSE_A2

PSE_A4

PSE_B1

PSE_B3

PSE_B5

VEC_CON1_2

VEC_CON1_4

VEC_CON2_1

VEC_CON2_3

VEC_CON2_5

Subsystem dose point

EPFL ong>Spaceong> Center 9th June 2009

An accurate spacecraft model

will increase the accuracy of

dose requirements

Top Level Requirement

XPOND_A2

XPOND_A4

XPOND_B2

XPOND_B4

XPOND_C2

XPOND_C4


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Monte Carlo Particle Transport

• Detailed radiation “transport” calculations provide a more accurate

treatment of the radiation interaction processes. Calculates:

– particle numbers, species, energy, ong>andong> 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

– Geant4 based tools

– NOVICE

– MCNPX (limited accessibility)

EPFL ong>Spaceong> Center 9th June 2009

Geant4 simulation of ISS ATV module


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

Conclusion

• Defining the space radiation environment is an

essential input to cope with radiation effects in

EEE components during space missions.

• Numerous future challenges:

– Need for updated, more accurate ong>andong> dynamic

models taking into account e.g. solar cycle activity

variations…

– Better predictions of space weather is essential for

future manned missions to the Moon ong>andong> Mars.

– Improved models would help produce more reliable

ong>andong> cost-effective spacecrafts ong>andong> facilitate the

implementation of new space technologies

EPFL ong>Spaceong> Center 9th June 2009


ong>Spaceong> ong>Radiationong> ong>andong> ong>itsong> ong>Effectsong> on EEE Components

References

• IEEE NSREC Short courses

• RADECS Short courses

• ECSS-E-10-04

• The near-Earth ong>Spaceong> ong>Radiationong>

Environment, S. Bourdarie et. al., IEEE

Trans. Nucl. Sci., Vol. 55, No. 4, Aug.

2008

• www.spenvis.be

• http://trad.fr/OMERE-Software

EPFL ong>Spaceong> Center 9th June 2009

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