2010/ 9/ 222010/ 9/ 2211th Spacecraft Charging Technology Conference
New Mexico, USATemperature Dependence on Electrostatic
Discharge in a Simulated Space Plasma
,
Discharge in a Simulated Space Plasma Environment
T, Okumura. J, Harada. Y, Hagiwara. K, Nitta. M, TakahashiJapan Aerospace Exploration Agency
T, Toshimitsu. K, ToyodaKyushu Institute of Technologyy gy
BackgroundNo2
Time
tial
Vcgee
e e
Pote
nt
e e ee
Vsat
Depends on temperature??Depends on temperature??Discharge number estimationgProper experiment condition for ESD test
Collaboration researchNo3
Temperature dependence on primary discharge
JAXA KITThreshold LEO
Temperature dependence on primary discharge
JAXA KITThreshold GEOThreshold voltage
LEO
Discharge LEO
Threshold voltage
GEO
Discharge LEOfrequencyfrequency
No4
Threshold of differential voltageThreshold of differential voltage
Experiment technique and result
Experiment system (JAXA)No5
Electron beam gunSurface potential meter
IR camera
PC
PCPC
Discharge positionTemperature monitor
Vb
Cext V
Analog signalOSC
Discharge circuitHeat panel
Shroud
OscilloscopeDischarge circuitHeat panel
Solar array couponNo6
35mm75
mm MJ cell
CG =100m7
Experiment system (JAXA)No7
Shroud
Solar array couponXY stageTREK
H t l
Solar array coupon
Heat panel
Experiment conditionNo8
• Pressure: 5x10-5PaPressure: 5x10 Pa• Current density: 4mA/m2
A l i l 9k• Acceleration voltage: 9kV• Bias voltage: 6kV
Discharge circuitNo9
C5C3C2C1
Rb280pF
C4
Rb280pF
VbV Vp
CB
Test sequenceNo10
Surface potential distribution
Beam irradiation
NoDischarge?
Elapsed timeYes
No
YesNo
Elapsed timex sec
Surface potential distribution
Discharge position and current waveform No11
20’C -110’C
Discharge position and surface potentialNo12
20’C -110’C
Surface potential profileNo13
Threshold voltage
Charging speed
Low temperature Room temperatureLow temperature Room temperature
Threshold volatageNo14
Room Low temperature temperature
Threshold 1.3kV 1.4kVvoltage
Standard 0.5 0.1deviation
Threshold voltage does not depend on the temperatureon the temperature
No15
Discharge frequencyDischarge frequency
Experiment technique and result
Experiment system (KIT)No16
ECR plasma sourcePC
QMASS
IR camera
PC
PC
Discharge positionShroud
Vb
Cext V
Analog signal OSC
Discharge circuit
Sheet heater
OscilloscopeDischarge circuit
Experiment system (KIT)No17
ShroudQMAS ShroudQMAS
Solar array coupon
Solar array couponNo18
35mm
75m
m
MJ cellCG =100mCG 100m
Test sequenceNo19
Expose to air for 3hours
Experiment: Room temperature for 60min
p
Increase the temperature by seat heater Increase bias voltage
Experiment: High temperature for 60min
Decease the temperature by LN2
Experiment: Low temperature for 60min
Experiment conditionNo20
CouponVbias[
V]Experimenttime[min] Ne[1/m3] Te[eV] Pressure
[Pa]
Coupontemperature[ ]High room lowh
-200 60 6×1012 0.7 2.9×10-264~66
30~31
-34~
-29
-300 60 7×1012 0.7 2.7×10-264~65
30~30
-42~
-34
-400 60 7×1012 0.7 3.6×10-263~65
20~39
-46~
-33
Temperature dependence on discharge numberNo21
Bias Room(30℃) High(60℃) Low(-30℃)-200 0 1 6-300 3 9 28-400 15 11 60
Discharge frequencyLow temperature Room temperaturep p
Same result as JAXA
SummaryNo22
• Threshold differential voltage does not depend on temperature g p pin GEO environment
• Arc frequency increases with decreasing temperature in JAXA d KITand KIT
• Discharge number estimation• Discharge number estimation– We need to concern the temperature to estimate the charging speed of
insulation material
i di i f S• Proper experiment condition for ESD test– In terms of GEO environment test to investigate the threshold voltage,
we do not need to care about the temperature
Future workNo23
• ESD test under GEO environment in KITESD test under GEO environment in KIT• Absorbed material effect on discharge
frequencyfrequency
