Spacecraft bus voltage and power 0.1 1 10 2 3 4 1001000 DSCS II RCA SATCOM MILSTAR TDRS SKYLAB SPACE TELESCOPE LEASAT ISS HS702 space factory 、 space hotel.

Spacecraft bus voltage and power

0.1

1

10

102

103

104

10 100 1000

DSCS II

RCA SATCOM

MILSTAR

TDRS

SKYLAB

SPACETELESCOPE

LEASAT

ISS

HS702

space factory 、space hotel

Spa

cecr

aft p

ower

(kW

)

Bus voltage(V)

EOS-AM

ETS-8

Before mid-90sAfter mid-90sAfter 2010

experimentalsolar power satellite

severe plasma interaction

400V is necessaryfor next-generation1MW large space platform after ISS

Spacecraft potential in LEO

load

φ1

φ2

φ1

electrons

ions

Varray=φ1 +φ2

φ2 ≈−Varrayd

plasmapotential+ +++ + +

+

+

+

+++++++

++

+

+

+

Charge accumulated over the total area

φ2 =φs

φinsl≈−κTe

Q=εdVarrayA

d+12CcgVarray

φcg≈−κTe

ΔV=φinsl−φs ≈−κTe +Varray≈Varray

ΔV

+

+

+

+

+++++

How an arc occur?

e

ii

ii e

ee

sheathcoverglass (dielectric)

solar cell

interconnector (conductor)substrate(dielectric)

triple junction

e

+ + + + +

eeee

ee

+++

+

+ + + + + + + + + + + +

e

+ + + + + + + + + + + ++++ +

++

eee

ee

e

+

+

+

+

+

+ + + +

+

++

+++

+ ++

Charging of coverglass by ions

Field intensification at triple junction

Field emission of electrons

Ionization of desorbed gas

Neutralization of coverglass charge

Repeated arcing and charging process

Sustained arc

- + - + - +

triggerarc

growth of arc plasma

sustainedarc formation

(a) (b) (c)

Test facility

R

B

G

7cm

3.5cm

21cm

P bus bar

N bus bar

inter-connector

21cm

18cm

RTV

Xe ionthruster

Large-scaleDeployableReflector(LDR)

7.3m

40m37m

2.35m

2.45m

12.8m

2.4m

satellite potential

φcg≈φs≈1~2V

Onset ofsubstorm

differential voltageΔ ≈V kV

coverglass potential

Potential

time

φcg

φs

GEO Plasma Environment Test Chamber

• Operational since March 2002• Diameter 60cm, Length 90cm• Minimum Pressure 3x10-7Torr• Equipped with an electron beam gun, a non-contacting surface potential probe, a Kaufman type plasma source, a xy-stage,

a low-pressure mercury lamp, halogen heat lamps, a video-image analysis system

Electron beam (max30kV)

Trek probe

X-Y stage controller

Trek probe

Solar array coupon

X-Y stage

LEO Plasma Environment Test Chamber

•Operational since 1998•Diameter 1m, Length 1.2m (excluding sub-chamber)•Minimum pressure 1x10-6Torr•Plasma density 1x1012m-3 or above•Equipped with an ECR plasma source, a deuterium UV lamp, a mass spectrometer, a x-y stage, a video-image analysis system, a high speed data acquisition system, halogen heat lamps, a spectrum analyzer, a metal-halaide lamp

Pressure chamber(1 MPa)

= 600 mm

time

time

Vfo

density

temperature

temperature

density

Vfo

Measurement of gas properties Measurement of flashover voltage

Build-up of database

Distribution of charge exchange ions and neutralizer electrons near a GEO satellite with an ion thruster

Ion density Electron density

Example of three-dimensional simulations

x

y

z rB

rvd

0 20 40 60

electron density

Magnetic field

plasma flow