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?
11th SCTC-Albuquerque september 2010
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
11th SCTC-Albuquerque september 2010
JONAS
11th SCTC-Albuquerque september 2010
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
11th SCTC-Albuquerque september 2010
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
11th SCTC-Albuquerque september 2010
See poster n°49
FO signals
80
A)
50
60
70I (A
BOFO S1
30
40
FO S3FO S2FO total
0
10
20
11th SCTC-Albuquerque september 2010
-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
11th SCTC-Albuquerque september 2010
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
11th SCTC-Albuquerque september 2010
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
11th SCTC-Albuquerque september 2010
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
11th SCTC-Albuquerque september 2010
-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
11th SCTC-Albuquerque september 2010
•
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)
11th SCTC-Albuquerque september 2010
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
11th SCTC-Albuquerque september 2010
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
11th SCTC-Albuquerque september 2010
Set-upIABGPlasmachamber
2 Electron guns
source
Solar panel2m*4m
Surface potentialmeasurement
11th SCTC-Albuquerque september 2010
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)
11th SCTC-Albuquerque september 2010
11th SCTC-Albuquerque september 2010
11th SCTC-Albuquerque september 2010