28
-24, 2010 rque, NM, September 20- ogy Conference, Albuquer ecraft Charging Technolo 11th Space 1

que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

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Page 1: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

-24,

201

0rq

ue, N

M, S

epte

mbe

r 20-

ogy

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nce,

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uque

rec

raft

Cha

rgin

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chno

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pace

1

Page 2: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Comparison of numerical and experimentalComparison of numerical and experimental investigations on the ESD onset in the Inverted

Potential Gradient situation in GEO

P. Sarrailh, J.-C. Matéo-Vélez, J.-F. Roussel, B. Dirassen (ONERA)

11th Spacecraft Charging Technology Conference, Albuquerque, NM, September 20-24, 2010

, , , ( )J. Forest, B. Thiébault (ARTENUM)

D. Rodgers, A. Hilgers (ESA)

Page 3: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Outline

• General overview on the ESD risk• Experimental setup

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p p• SPIS ESD tool• Parametric study: comparison experimental/numerical results

rque

, NM

, Sep

tem

ber 2

0-og

y C

onfe

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e, A

lbuq

uer

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Tech

nolo

11th

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ce

3

Page 4: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

General overview on the ESD risk

Page 5: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Spacecraft Charging at GEO in sunlight

• S/C structure at a negative potential several kV due to electron collection• Photoemission on solar cell cover glass:

• Dielectrics in sunlight more positive than S/C structure

-24,

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g p• Barrier of potential on the front side due to rear side negative potential

• This situation is the Inverted Potential Gradient (IPG)

net photo electron current

rque

, NM

, Sep

tem

ber 2

0-

saddle point - 2010 V

- 1500 V

hυrecollected electrons

ogy

Con

fere

nce,

Alb

uque

r

S/C SA SA

- 2800 V

- 2000 Vfront side

rear side - 3000 V

electrons

ecra

ft C

harg

ing

Tech

nolo

- 2500 V

- 2200 V ibl t j t i f

2010 V

11th

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ce

5

- 2010 V

- 1500 V

Page 6: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

IPG situation at the solar cell scale

• At the solar cell edge:• Gap surface covered with (photoconductive) kapton = S/C structure voltage• Solar cell voltage ~ S/C structure voltage (strings voltage ~100 V)

-24,

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0

• Cover Glass top surface is more positive than solar cell = differential voltage• Triple point between conductor, dielectric and vacuum

• Uses of a simplified geometry (valid for interconnects) to compare experimental and

rque

, NM

, Sep

tem

ber 2

0- numerical results

-2200 V-2400 V

-2600 V

-2800 VFront surface

barrier potential

he-

ogy

Con

fere

nce,

Alb

uque

r

Triple point

Coverglass

-2000 V

Glue

Front surface

Side surface

he

e-e-

Differential voltage

ecra

ft C

harg

ing

Tech

nolo

Dielectric layer

Triple point

Solar Cell ~ -3000 V

Glue

-3000 V~ -3000 V

Glue

metal

dielectrics

Differential voltage

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ce

6

Structure S/C stucture potential

Page 7: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Microscopic structure and electron avalanche

Simulation at mesoscopic scale

Microscopic scale model

-24,

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0

Fowler-Nordheim e-

rque

, NM

, Sep

tem

ber 2

0-

electric field amplification due to micron tipdielectrics

ogy

Con

fere

nce,

Alb

uque

r

metal

Differential potential

Electric field onSecondaryElectron avalanche

+

ecra

ft C

harg

ing

Tech

nolo

Secondary emission by electron impact + recollection

Electric field on the tip

Fowler-Nordheim

Secondary emission > 1 Cathode spot creation

=> ESD

11th

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7

electron emission

Page 8: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Tip geometry and field enhancement factor

• Field enhancement factor from 300 to 800• Tip length: 1 m • Tip radius (from emitting area): 1 - 10 nm

-24,

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0rq

ue, N

M, S

epte

mbe

r 20-

ogy

Con

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nce,

Alb

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rec

raft

Cha

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• Figure 5 and figure 8 extracted from:Effect of electrode surface finish on electrical breakdown in vacuum, D W Williams and W T

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8

Williams, J. Phys. D: Appl. Phys. (5), 1972.

Page 9: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Experimental setup

Page 10: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Experimental Setup

• ONERA CEDRE vacuum chamber• Pressure: 3.10-6mbar• Barrier potential controlled by Vbias

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Barrier potential controlled by Vbias

• Differential voltage by photoemission (as in flight)

Rotatingcubic holder

UV sourceElectrostatic probe

rque

, NM

, Sep

tem

ber 2

0-

HV Feedthroughs Electrostatic probecubic holder

Metal

Dielectric

ogy

Con

fere

nce,

Alb

uque

r

UV sourceSample

tank walls

Csat =

I

ecra

ft C

harg

ing

Tech

nolo

CCD Camera

CEDRE chamber

VbiasCsat 10nF

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Page 11: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Nominal case – Perpendicular TP with Aluminum and Teflon

• The triple point is irradiated by the UV source• Only the chosen triple point line can generate

3mm

Al

UV

Irradiated zone

-24,

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0

y p p gESDs thanks to a protecting mask 40mm

Dielectric FEP with aluminization on the rear side Protecting mask

rque

, NM

, Sep

tem

ber 2

0-

Al

g

ogy

Con

fere

nce,

Alb

uque

r

UV Irradiation zone

FEP

ecra

ft C

harg

ing

Tech

nolo

sample

UV protection

11th

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11

200 mmUV protection mask

Page 12: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Nominal case – Perpendicular TP with Aluminum and Teflon

• The voltage on the FEP is close to 0V • 8 ESDs have been obtained at 1 5

2

2,5

3

A

ESD #1ESD #2ESD #3

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0

different locations of the triple point edge

• The ESD threshold is about -800V -0,5

0

0,5

1

1,5

curre

nt, A ESD #4

ESD #5ESD #6ESD #7ESD #8

rque

, NM

, Sep

tem

ber 2

0- -1-5 0 5 10 15 20

Time, µs

2,5

ogy

Con

fere

nce,

Alb

uque

r

1,5

2

curr

ent,

A

ecra

ft C

harg

ing

Tech

nolo

0

0,5

1Pe

ak

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12

00 200 400 600 800 1000

Differential voltage threshold, V

Page 13: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Results of the parametric study

6Nominal caseMetal length 15mm

-24,

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0 4

5

nt, A

Metal length 15mmCMX AR dielectricChange of incidence angleGold

rque

, NM

, Sep

tem

ber 2

0-

2

3

eak

curr

e Co planar (5nF)

ogy

Con

fere

nce,

Alb

uque

r

1

2P

ecra

ft C

harg

ing

Tech

nolo

00 500 1000 1500 2000 2500

Differential voltage threshold, V

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Differential voltage threshold, V

Page 14: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

SPIS ESD tool

Page 15: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

The mock-up geometry and the boundary conditions

UV• Simulation conditions:

• Teflon (127 m) / aluminum (1.5 mm)• External box : 4 cm x 4 cm x 0.6 cm

x

z

40mm

UV

Irradiated zone

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• TP zone : 1 m• tip length = 1 m• Barrier potential from 500 V to 2000V• from 800 to 300;

3mm

40mm

Al

rque

, NM

, Sep

tem

ber 2

0-

Barrier potential(Dirichlet condition) Refinement

boxTriple point with field

enhancement

;Dielectric FEP

ogy

Con

fere

nce,

Alb

uque

r

Symmetry conditions

enhancement

ecra

ft C

harg

ing

Tech

nolo

YZ

YX

Z

PerpendicularX

Y

Z

z

x

y

x

z

x

y

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15

Y p

Metal plane + triple point(Dirichlet; V = 0)

Dielectric(implicit solver)

Page 16: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

SPIS ESD tool

• ESD prediction scenario, two imbricate loops:• Barrier potential prediction• Tip geometry evaluation: field enhancement factor

loop (for a fixed tip length – 1m standard)

Tip and potential P t ti l

ESD prediction scenario

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Data from UI

Init simulationFN current calculation

TipRecession interactor

FN current calculation

TipRecession interactor

no

Simulation Loop

yesno

Next time-step

Same potentialNext tip (lower

p pre-initializationPotential sweep

rque

, NM

, Sep

tem

ber 2

0-

Plasma integration

SC/Plasma interactions simulationDt

ScenarioPower balance on tip

Tip temperature

Mass losses by evaporation

Neutral density

Power balance on tip

Tip temperature

Mass losses by evaporation

Neutral density

noESD ?

yes

Is the tip melted ?

ogy

Con

fere

nce,

Alb

uque

r

x

RR

Circuit solver

simulationDuration

Scenario end ?

simulationLoop

Tip length

evaporation

New

Ionization probability

ESD ?

Tip length

evaporation

New

Ionization probability

ESD ?

ecra

ft C

harg

ing

Tech

nolo L

Scenario end ?

Results to UI

• Tip model (tipRecession interactor):• Tip model based on a cylindrical geometry

11th

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• Tip model based on a cylindrical geometry• Zero dimensional thermal model (compared to Rossetti ….)

Page 17: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Barrier potential and emitted currentste

ntia

l (V

)

1500

2000

-24,

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0

Bar

rier p

ot

0

500

1000

ESD T i

ESD Trig. = 650

ESD Trig. = 600

rque

, NM

, Sep

tem

ber 2

0-

)

10-4

1ESD Trig. = 800

ESD Trig. = 750

ESD Trig. = 700

650

Ph t i i

ogy

Con

fere

nce,

Alb

uque

r

Cur

rent

(A)

10-12

10-8

Fowler-Nordheim emission

Photoemission

ecra

ft C

harg

ing

Tech

nolo

0 50 100 150 200 250 300 350 40010-20

10-16

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0 50 100 150 200 250 300 350 400

Time (s)

Page 18: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Electron emission : densities in volume-2

4, 2

010

rque

, NM

, Sep

tem

ber 2

0-

Dielectric Metal Dielectric Metal

ogy

Con

fere

nce,

Alb

uque

r

S d l t d itF l N dh i l t d it

DielectricMetal

DielectricMetal

ecra

ft C

harg

ing

Tech

nolo Secondary electrons densityFowler-Nordheim electrons density

• F-N primary electrons:• directed toward the barrier potential

M d it h 1020 3 (S h ff t)

11th

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• Max density can reach 1020 m-3 (Space charge effect)• Secondary electrons are present on the top side of the dielectric due to hoping

Page 19: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Parametric study: comparison of the numerical and experimental results

Page 20: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Parametric study – reference case

6

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0

4

5 Reference caseAluminum-Teflon 127 m3 mm Gap

3mm

40mm

rque

, NM

, Sep

tem

ber 2

0-

3

4

ak c

urre

nt (A

)

Irradiated Gap

ESD Trig. = 800

ESD Trig. = 600

3mm

ogy

Con

fere

nce,

Alb

uque

r

2

Pea 800 600

ecra

ft C

harg

ing

Tech

nolo

0

1

500 1000 1500 2000 2500

Experimental resultsNumerical results

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Differential voltage (V)

Page 21: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Parametric study – Sun incidence angle

6

Not Irradiated Gap

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4

5 Reference caseAluminum-Teflon 127 m3 mm Gap

Not Irradiated GapAluminum-Teflon 127 m3 mm Gap

rque

, NM

, Sep

tem

ber 2

0-

3

4

k cu

rren

t (A

) Irradiated Gap

400V 3mm

40mm

ogy

Con

fere

nce,

Alb

uque

r

2Peak

350V

3mm

ecra

ft C

harg

ing

Tech

nolo

0

1

500 1000 1500 2000 2500

Experimental resultsNumerical results

11th

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Differential voltage threshold (V)

Page 22: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Parametric study – Gap length

6

15mm Gap

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4

5Reference caseAluminum-Teflon 127 m3 mm Gap

15mm GapAluminum-Teflon 127 mIrradiated Gap

rque

, NM

, Sep

tem

ber 2

0-

3

4

ak c

urre

nt (A

)

Irradiated Gap

900V 3mm

40mm

ogy

Con

fere

nce,

Alb

uque

r

2

Pea

800V

ecra

ft C

harg

ing

Tech

nolo

0

1

500 1000 1500 2000 2500

Experimental resultsNumerical results

11th

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Differential voltage threshold (V)

Page 23: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Parametric study – Dielectric material

6

Aluminum-CMX 100 m3 mm Gap

-24,

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0

4

5

)

Reference caseAluminum-Teflon 127 m

3 mm GapIrradiated Gap

rque

, NM

, Sep

tem

ber 2

0-

3

4

k cu

rren

t (A

) 3 mm GapIrradiated Gap

CMX-AR □ = 2.6×1016

CMX-AR □ = 1016

CMX-AR □ = 5×1015

ogy

Con

fere

nce,

Alb

uque

r

2Peak

Teflon □ = 1016

3mm

40mm

ecra

ft C

harg

ing

Tech

nolo

0

1

500 1000 1500 2000 2500

Experimental resultsNumerical results

11th

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23

500 1000 1500 2000 2500Differential voltage threshold (V)

Page 24: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Lessons to be taken from the experiments and numerical simulations

• The numerical results qualitatively agree with the experiments• It is definitely more difficult to trig ESDs in the following cases

-24,

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• Low photon incidence angle• Longer metallic plate• Co-planar geometry

More conductive dielectric

rque

, NM

, Sep

tem

ber 2

0- • More conductive dielectric

• Strong effect of • surface resistivity of the front edge

ogy

Con

fere

nce,

Alb

uque

r • surface resistivity of the front edge• Tip geometry (radius and shape)

• Need for complementary experimental data (surface resistivity measurement,

ecra

ft C

harg

ing

Tech

nolo

p y p ( y ,surface distribution and type of microscopic structures)

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Page 25: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Conclusion

Page 26: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Conclusion

• Large experimental parametric study

-24,

201

0

• SPIS ESD tool:• Complete ESD scenario:

• 3D Electron avalancheThermal model of the tip

rque

, NM

, Sep

tem

ber 2

0- • Thermal model of the tip• ESD threshold estimation

• Simulation of the charging and electron avalanche well described• Automatically adapted time steps: from 1s to 10-12s

ogy

Con

fere

nce,

Alb

uque

r Automatically adapted time steps: from 1s to 10 s• 3 length scales simulated

• Good qualitative agreement between experiments and numerical results

ecra

ft C

harg

ing

Tech

nolo

q g p

• Need of further experimental data to provide design engineers with quantitative/predictive ESD risk tool

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Page 27: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Perspective

• Experimental investigation on surface resistivity to get more data

-24,

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0

• Photo conductivity modeling improvement

• More complex geometry:

rque

, NM

, Sep

tem

ber 2

0-

p g y• solar cell edge • here, it is close to the interconnects

ogy

Con

fere

nce,

Alb

uque

r

• Effect of multiple tips (tip distribution on the surface)

• Emission from semi-conductors

ecra

ft C

harg

ing

Tech

nolo

• Model the plasma generation during the transition to arc

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Page 28: que, NM, September 20 gy Conference, Albuque craft Charging …€¦ · Spacecraft Charging at GEO in sunlight • S/C structure at a negative potential several kV due to electron

Questions ?