Di t t lDistant arcs on solar array coupons: Is the ESD in ... · Di t t lDistant arcs on solar array coupons: Is the ESD in the gap the most critical situation? V. Inguimbert 1,

Di t t lDistant arcs on solar array coupons:

Is the ESD in the gap the most critical situation?

V. Inguimbert1, D. Sarrail1, J.-M. Siguier1, J.-C. Matéo-Vélez1, D Payan2 N Balcon2D. Payan , N. Balcon

1 ONERA/DESP, 2, Avenue Edouard Belin, 31 055 Toulouse cédex, France2 CNES, 18 Avenue Edouard Belin, 31 401 Toulouse cédex, France

Outline

• Context, objectivesSet up• Set-up

• physical FO simulator

• Results• Discussion

11th SCTC-Albuquerque september 20102

Context - Objectives

• ESD qualification of solar array coupons Constant discussions/reflexions on the qualification set up• Constant discussions/reflexions on the qualification set-up(ex ISO doc)

• Most critical situation is generally agreed to be the ESD in the gap

• Does a discharge elsewhere can provoke an arc between cells?cells?

• Does distant arcs exist?• If yes, can it be more critical?


Test conditions

• Reproduce the situation usually used for solar arrays coupons qualification (against ESD risk)

• Inverted voltage gradient• SAS

• Instead of leaving only the gap apparent, leave also interconnectors

?

• Usual configuration configuration of this test

• Use FO simulator developped by ONERA/CNES


JONAS


Experimental set-up

plasma

SAS

1.1kΩ

Va Vin

Kapton Metallization

10µF

HC

50kΩ

20kΩ

Kapton Metallization

Vbias

Csat=300pF or 10nF

5

inside JONASchamberi


Flash over simulator(metallized kapton)

iBO

Experimental set-up

Solar cells coupon Metallized Kapton JONAS vacuum chamberSolar cells coupon Metallized Kapton JONAS vacuum chamber

Plasma source

FO C t b

Plasma source

FO C t b

S1 S2 S3

50k Ω

HV

Csat

FO Current probe

BO Current probe

50k Ω50k Ω

HV

Csat

FO Current probe

BO Current probe

i4 i5 i2 i3

HV BO Current probeHV BO Current probe


See poster n°49

FO signals

80

A)

50

60

70I (A

BOFO S1

30

40

FO S3FO S2FO total

0

10

20


-10

0

-1,0E-04 0,0E+00 1,0E-04 2,0E-04 3,0E-04 4,0E-04

time (s)

See poster n°49

ESD 165 ( Csat = 10 nF) – on IC

2

Time (s)urre

nts

(A)

-2

0-1.0E-04 1.0E-04 3.0E-04 5.0E-04 7.0E-04

C

gap

-4

-2

ESDarc

-6Total FO /5Arc currentBO *5

-8

arc duration = 150µsdelay = 41µs


delay = 41µsdistance = 19mm

ESD n°196 (Csat=330pF)3

ESD196 (Csat = 330pF) – on ICESD n 196 (Csat 330pF)

0

1

2

Cur

rent

s (A

)

-2

-1

0-1,0E-04 1,0E-04 3,0E-04 5,0E-04 7,0E-04

Time (s) gap

-5

-4

-3

Arc current

-7

-6

5Total FO /5

-8 arcarc duration = 420µsdelay = 160 µs


ESDdelay = 160 µsdistance = 32 mm

ESD 230 (Csat = 330pF) – in the gap

ESD n°230 (Csat = 330pF)

1

2

3

Cur

rent

s (A

)

2

-1

0-1.0E-04 1.0E-04 3.0E-04 5.0E-04 7.0E-04

Time (s)

C

ESD and arc

-4

-3

-2 ( )

Arc current

Total FO /5

-7

-6

-5 BO *5

arc duration = 500µsdelay = 2.5 µs


distance = 0 mm

Summary of results

250

300(µ

sec)

200

250

dela

y (

100

150

50

100

Csat = 330 pF

0

00 5 10 15 20 25 30 35 40 45

Distance (mm)

Csat = 10nF


-50 Distance (mm)

Discussions

• Phenomenon?• cathode shifting with creation of a second cathodic spot?

• Observed when the primary discharge occurs on the string +• Observed inside slip rings• Observed inside slip-rings

• anode spot creation on the adjacent cell?• Relation distance/delay?

• Velocities :• fast electrons : ~ 106 – 107 m/s• FO plasma : ~ 104 m/s

• Creation of an anodic spot :• maybe possible if the collected current is > current threshold • i.e. if local plasma density is > density threshold n0• n(x,t) ~ 1/x² * i(t) ( i(t) source of plasma at discharge point (~ t²))• n(x,t) ~ t²/x² n(x,t) > n0 => t > x * Constant

• => linear dependance between the delay and the distance


•

Discussion - conclusion

Position ESD In the gap Elsewhere(identified)*

Elsewhere(non id tifi d)identified)

Number of identified discharges 20 17 53

N b f i d d d 19 11* 7Number of induced secondary arcs

19 11* 7

% 95% 65%

* those which did not induce arcs where situated at a distance < 40mm from the closest gap

• All ESDs in the gap induced long arcs (stopped by current limiter)


Conclusion

• Distant arcs are possibleThey appear after a certain delay related to distance• They appear after a certain delay related to distance

• Delay attributed to the time needed to obtain a sufficient plasma density to create an anodic spot

• ESD in the gap is the most probable to induce an arc


Flash-Over evaluation on large solar panelsFlash-Over evaluation on large solar panels"EMAGS 3"

V. Inguimbert (ONERA), C. Baur (ESA), D. Payan (CNES), A. Gerhard (ASTRIUM-Germany),P Pelissou (Astrium France) B Boulanger (TAS France) C Wuersching (IABG)P. Pelissou (Astrium- France), B. Boulanger (TAS-France), C. Wuersching (IABG)

+ many others

objectives

- Perform a test on a large solar panel to measure FO propagation:- maximum surface/distance- velocity- effect of different parameterseffect of different parameters

such as plasma/electrons IVG, low temperature…

- Consolidate ESD/arcing qualification test setup for solar array coupons


Set-upIABGPlasmachamber

2 Electron guns

source

Solar panel2m*4m

Surface potentialmeasurement


Preliminary Results

we have performed a test on a panel 4*2 m

we have observed discharges with a collection of current on every string

no major difference between test in plasma and tests in electrons has been observedelectrons has been observed

a further analysis has to be done on the corresponding ne tralised charge and on propagation elocitneutralised charge and on propagation velocity(papers to be published soon)




Documents

Di t t lDistant arcs on solar array coupons: Is the ESD in ... · Di t t lDistant arcs on solar array coupons: Is the ESD in the gap the most critical situation? V. Inguimbert 1,