Dusty Plasmas
Wing-Huen Ip
wingip@astro.ncu.edu.tw
Institutes of Astronomy and Space Science,
National Central University
The 1st CPS International School of Planetary Sciences,“Dust in Space”
January 5-9, 2009
Seapal Suma, Kobe, Japan

Outline• Prologue• Saturnian rings• Lunar dust
• Cometary and asteroidal dust
• Laboratory dusty plasmas• Summary• Epilogue

Basic references• Horanyi, M., Charged dust dynamics in the Solar System, Ann.
Rev. Astr. Astrophys., 34, 383, 1996.
• Shukla, P.K., A survey of dusty plasma physics, Phys. Plasmas,8, 1791, 2001.
• Ishihara, O., Complex plasma: dust in plasma, J. Phys. D:Appl. Phys., 40, R121, 2007.
• Morfill, G.E., Ivlev, A.V., Rubin-Zuzic, M., Knapek, C.A.,
Pompl, R., Antonova, T., and Thomas, H.M., Complex
plasmas-new discoveries in strong coupling physics, Appl.
Phys., B89, 527, 2007.
• Grasp, A.L., Jones, G.H., Juhasz, Al Horanyi, M. andHavnes,O., The charging of planetary rings, Space Sci. Rev.,
137, 435, 2008.

Lecture 1
January 6, 2009

1. Prologue

The first generation of dusty plasma physicists

W. Ian Axford

Asoka Mendis and Hannes Alfven

Saturn as A Dusty Plasma Laboratory

Alfven’s critical ionization effect and plasmacondensation model of the Saturnian rings

Europa

Titan for Christmas

From Athena Coustenis,
X’mas 2008

Surface albedo asymmetryof Saturnian icy satellites

Top-down model
Soter (1974) originallyproposed dust
Ejected from Phoebe could
land on theLeading hemisphere ofIapetus (see also Burns et al.
(1996).

Krivov and Banaszkiewicz (2001)

Annual Review of Earth and Planetary Science

Mendis & Axford (1974)

Bottom-up model

Surface erosion mechanism of Iapetus

Meteoroids~Ice sublimation

Mendis & Axford (1974)

2. Saturnian rings

Cassini view of the Saturnian ring system

Edge-on view of the E-ring by Keck
(Optical depth ~ 10-5)

de Pater et al. (2004)

Extended OH cloud

Jurac et al. (2001)

Saturnian Satellites

MET

DR

TitanIapetus

Enceladus’ gas and dust plumes

Burger et al. 2007

Dynamics of Saturn’s E-ring dust••••

R E = 4 Rs
N(O+) = 100 (RE/a)4
T(O+) = 100 eV
Perturbation effects:
Electrostatic charging
Planetary oblateness (J2)
Radiation pressure force
Plasma drag force• Ion sputtering time ~ 50 years for1 μm icy grains

Hamilton and Burns (1994)

Grain charging by thermal plasma•Current balance condition:
Je(Φd(t)) + Ji(Φd(t)) +Jsec(Φd(t)) + Jph(Φd(t)) =0•

Jph is photo-electron emission
currrent
Je,I are electron/ion currents
from the background plasma
Jsec is secondary electroncurrent••

Shull (1978); Whipple (1981);
Chow et al. (1993); Horanyi (1996)
Ishihara (2007)

The charging equation••
Ion and electron currents(Ii+ and Ie+) forsurface potential s>0(Mendis et al. ,1981):

WithThe photoelectron current Ip+ iswhere kTp =2 eV and X=0.1.
For s <0,Ii – Ie + Ip = 0 → s =？

Comparison of theoreticalmodels with Cassini CDA
observations of theelectrostatic potential of thecharged dust
Juhasz and Horanyi (2002)

Roussos et al., (2008)

Kempf et al. (2006)

E-ring particle density distribution• Top: rg ~ 0.1-0.5 μm• Middle: rg ~ 0.5-1.0 μm• Bottom: rg ~ 1.0-3.0 μm

Top to Bottom: 0.1, 0.3, 1 and 3 μm

Horanyi et al., (2008)

Saturn’s (B) ring spokes

Smith et al. (1981, 1982)

Time evolution of ring spokes

Jones et al., (2006)

Spoke statistics

Grun et al. (1984)

Porco and Danielson (1982)

Meteoroid-ring impact pattern

Erosionrate

Ip (1995)

The dusty plasma cloud modelof spoke generation

http://www.nasa.gov/images/content/205787main_PIA10081-226.jpg

Goertz and Morfill (1983)

Spoke formation under moving plasma clouds

Farmer and Goldreich (2005)

Ionosphere-dust cloud coupling

Farmer and Goldreich (2005)

Limitation to collective charging•••Surface electrostatic potentialof a dust grain embedded in adust cloud of number density(N) and Debye length (λD) isgiven by:
V = Vo(1+x) with
Vo = Q/a (a=grain radius)x = 4πNaλD2 e -R/λDa(1+λD)
The corresponding charge is:
Q = Qo/(1+x)
The sum of many small
potentials gives rise to an
average plasma potential
which is significantly
different from zero.
Goertz and Ip (1984)

Ring-ionosphere coupling•••

The self-generation (i.e., floatingplasma clouds) mechanism hasproblems.
An alternative effect is to invoke
external charging process, forexample, by injection of energetic
electron beams from the Saturnian
ionosphere (Ip and Mendis, 1986).
Saturn’s upper ionosphere hasstrong diurnal variation because of
precipitation of H2O and O2
molecules from the rings – asindicated by the thunderstormrelated SED (Saturn ElectrostaticDischarge) emission.

A new model is to generate
Energetic electron beams
by lightning.

Jones et al., (2006)

Red sprites produced by atmosphericthunderstorms

http://sprite.phys.ncku.edu.tw/new/news/0626_presss/
big_red_sprites_sentman_s.jpg

Valdivia et al. (1997)

Energetic electrons from lightning discharge

Lehtinen et al. (2001)

Lightning-induced ring spoke activity

Jones et al., (2006)

Diurnal and seasonal effects of ring charging

Ip (1984)

NASAFarrell et al. (2006): Spoke formation most probable on the negatively
charged side of the ring plane. This condition depends on thesolar inclination angle.

Ring O2 atmosphere and O2+ ionosphere

Tseng et al. (2009)

The shielding effect of an offset centereddipole fieldIp (1984)

A Cassini view of the A, B and C rings

CBASaturnian ring opacity variation from Cassin UVSI

Cassini Divisionfrom Janus 3:2?

?
e.g., Northrop & Hill (1983)

Force equilibriumIp (1983)

End of Lecture 1

Lecture 2
January 7, 2009

The first generation of dusty plasma physicists

W. Ian Axford

Asoka Mendis and Hannes Alfven

Annual Review of Earth and Planetary Science

Mendis & Axford (1974)

Bottom-up model

Surface erosion mechanism of Iapetus

Meteoroids~Ice sublimation

Mendis & Axford (1974)

Cassini view of the Saturnian ring system

Dynamics of Saturn’s E-ring dust••••R E = 4 Rs
N(O+) = 100 (RE/a)4T(O+) = 100 eV
Perturbation effects:
Electrostatic charging
Planetary oblateness (J2)
Radiation pressure force
Plasma drag force• Ion sputtering time ~ 50years for 1 μm icy
grainsHamilton and Burns (1994)

Horanyi et al. (2008)

Spoke formation on Saturn’s B ringMoving plasma cloud model vs. lightninginduced electron beam model

Goertz and Morfill (1983)

Jones et al. (2006)

Diurnal and seasonal effects of ring charging

Ip (1984)

NASAFarrell et al. (2006): Spoke formation most probable on the negatively
charged side of the ring plane. This condition depends on thesolar inclination angle.

Force equilibrium of charged small grains

CBAIp (1983)

3. The lunar dust

Lunar Horizontal Glow

Lunar horizontal glow drawn by
Apollo 17 astronauts

Moon-Solar Wind InteractionElectrostatic charging of lunar
surface

Stubbs et al. 2005

Electrostatic Charging of dustgrains• Ambient plasma electron flux (Ie)
• Ambient plasma ion flux (Ii)
• Photoelectron flux (Ip)

The charging equation••
Ion and electron currents(Ii+ and Ie+) for
surface potential s>0(Mendis et al. ,1981):

WithThe photoelectron current Ip+ iswhere kTp =2 eV and X=0.1.
For s <0,Ii – Ie + Ip = 0 → s =？

Electrostatic Fields• Solar wind plasmansw(d)=5*d-2 cm-3Te(d)=1.5*105*d-2/3 k
Ti(d)=105*d-2/3 kwith d in AU
Debye length:
Lsw = 6.9(Te/nsw)1/2 cm=38 m at d= 1 AU

• Photoelectrons
Solar photon flux(ε≧ 8ev )F=4.5*1012*d-2 photon cm-2‧s-1
Photoemission flux:
Ipe=∫0 200nm F(λ )X(λ)d λ=2.8*109*d-2 electrons/cm2/s( Willis et al.,1973)
Photo electron energy =kTpe~2 ev
Photo electron density
npe= 2Ipe/Vpe=70 cm-3
Lpe=6.9(Tpe/npe)1/2=3.8 m

Photoelectron density in the DebyeSheath• npe=npe(0) [1+z/√2λD] –2

with λD = Lpe(Grard and Tunaley, 1971)

Dust levitation
Global Sunlit sidecharging
E ~  / Lpe ~10-20
V/m• Terminator
Supercharging
E~1-3 KV/cm

Electrostatic charging of lunar dust

LADEE Mission of NASA (2012)
Lunar Atmosphere and Dust Environment Explorer
The objectives of the LADEE
mission are:Determine the global density,composition, and time variability of
the fragile lunar atmosphere before itis perturbed by further humanactivity;
Determine if the Apollo astronautsightings of diffuse emission at 10sof km above the surface were Na
glow or dust and;Document the dust impactor
environment (size-frequency) to help
guide design engineering for theoutpost and also future robotic
missions.

The NASA Dawn Mission
to Vesta and Ceres

Horizontal glow at Vesta orCeres?

Hayabusa Sample Return Mission

Rosetta Mission to 67P/Comet ChuryumovGerasimenko (2015)

4. Laboratory dusty plasmas

Missions to Halley’s Comet

SuiseiSakigake

Dust acoustic waves and dust ion acousticwaves
Rao, Shukla and Yu (1990)
Shukla and Solin (1992)

Liao et al. (2008)

The discovery of plasma crystals in 1994
Direct observation of Coulomb crystals and liquids in strongly coupled rf dusty plasmas
J.H. Chu and Lin I
Phys. Rev. Lett., 72, 4009, 1994

•The strongly coupled dusty
plasmas are formed bysuspending negatively charged
SiO2 fine particles with 10 μm
diameter in weakly ionized rf Ar
discharges. The Coulomb
crystals and liquids are directly
observed for the first time using
an optical microscope. By
properly controlling the systemparameters, hexagonal, fcc andbcc crystal structures and solids
with coexisting different crystal
structures can be formed.
Increasing the rf power causes
the transition to the moredisordered liquid state.

The discovery of plasma crystals in 1994
Plasma crystal: Coulomb crystallization in a dusty plasma
H. Thomas, G.E. Morfill, V. Demmel, J. Goree, B. Feuerbacher and D. Moehlmann
Phys. Rev. Lett., 73, 652, 1994

•A macroscopic Coulomb crystalof solid particles in a plasma has
been observed. Images of a cloudof 7-μm "dust" particles, which
are charged and levitated in a
weakly ionized argon plasma,
reveal a hexagonal crystal
structure. The crystal is visible tothe unaided eye. The particles arecooled by neutral gas to 310 K,
and their charge is >9800e,
corresponding to a Coulomb
coupling parameter Γ>20 700.
For such a large Γ value, strongly
coupled plasma theory predicts
that the particles should organize
in a Coulomb solid, in agreementwith our observations.

3D dust clusters (Yukawa balls)

Melzer, Kading, Block and Piel (2008)

Laser heating of 2D Yukawa monolayer of dusty
plasmas: Transition from solid to liquid

Nosenko and Goree (2006)

Plasma condensationin laboratory experiments and Tokamaks

Ishihara (2007)

Plasma condensates and interplanetary dust

Watanabe (2006)

Dust formation and sedimentation

From Sho Sasaki

The upper layer of the solar nebula is subject to the Balbus-Hawley instability
in driving the turbulence/viscosity while the mid-plane is a dead zone.
The first generation of dust condensation must be influenced by charging effect.

Cometary ice & interstellar grains

FIR Spectroscopy of icy grains analogs

光 譜
儀H
H

H 2 O:CO 2:NH 3 = 1:1:1

Absorbance

1.5

1.0
CO 2

0.5
CO 2

0.0
4000

NH 3

13

CO 2H 2O

3500

NH 3

NH 3

2500

2000

1500

1000-1

Wavenumber (cm )Intensity ( Arb. )

80

Ser60

Asp

Thr
Gly

40

Arg*

Ile*

ValAlaPhe*

GluGln*

Leu*
Lys*

Pro

Tyr*

200* Tentative identification

0246810121416

Retention Time ( min )Amino acids!

18

1.00E-011
5.00E-012

12C - Residue

0.25
0.20

NH 2stretching

C=Ostretching

0.15

0.00E+000
amu61
amu62

H 2O+CO 2+NH 3 = 1:1:1

2.00E-011

1.00E-011

0.10

1.50E-011

0.05

1.00E-011

amu61
amu62

13-0.05
4000500

NH2 bending

12

H 2O+ CO 2+NH 3 = 1:1:1

0.30

H 2O+ CO 2 +NH 3 = 1:1:1

0.00

H 2O

H 2O

3000

Relative Absorbance

0.35

CO 2

amu61
amu62

H 2O+CO 2 = 4:1

1.50E-011

OOHH

13

H 2O+ CO 2+NH 3 = 1:1:1

H
H 2.00E-011

C
CIon Current ( A )

2.0

O
O
N
N

0.40

13

3500

3000

5.00E-012

C - Residue
2500

2000

1500
-1

Wavenumber ( cm )

1000

500

0.00E+000
75100

125

150

175

200

Temp ( K )

225

250

275

300

Dusty plasmas are life-giving!

Summary Dusty plasma effects play an important role in smallscale (spokes) and large-scale structures (massdistribution) of the Saturnian main rings and the E ring.
 Many small solar system bodies including the Moon andCeres could be covered by a sheath of dusty plasmas.
 Laboratory experiments led to discovery of plasma
crystals which have wide applications (including solidstate physics, Tokamaks and quark-gluon plasma afterBig Bang).
 Plasma condensation and ion- or photon-interaction withdust grains could be important in astrophysical andplanetary environments.
We are working on all four topics of dusty plasmas
at National Central University.
Scientific collaborations are very welcome.

Epilogue

Iapetus from Cassini

Revisiting Iapetus after Cassini

Mendis and Axford (2008)

End of Lecture 2

References••••••••••••••••

Burger, M. H., Sittler, E. C., Johnson, R. E., et al. 2007, JGR, 112, A06219
Burns, J. A., Hamilton, D. P., Mignard, F., et al. 1996, ASPC, 104, 179
Chow, V. W., Mendis, D. A., & Rosenberg, M. 1993, JGR, 98, 19065
Chu, J. H., & I, Lin. 1994, PhRvL, 72, 4009
de Pater, I., Martin, S. C., & Showalter, M. R. 2004, Icarus, 172, 446
Farmer, A. J., & Goldreich, P. 2005, Icarus, 179, 535
Farrell, W. M., Desch, M. D., Kaiser, M. L., et al. 2006, GeoRL, 33, L07203
Goertz, C. K., & Ip, W.-H. 1984, GeoRL, 11, 349
Goertz, C. K., & Morfill, G. 1983, Icarus, 53, 219
Grard, R. J. L., & J. K. E. Tunaley 1971, JGR, 76, 2498
Grun, E., Garneau, G. W., Terrile, R. J., et al. 1984, AdSpR, 4, 143
Hamilton, D. P., & Burns, J. A. 1994, Science, 264, 550
Horanyi, M. 1996, ARA&A, 34, 383
Horanyi, M., Juhasz, A., & Morfill, G. E. 2008, GeoRL, 35, L04203
Ip, W.-H. 1983, JGR, 88, 819
Ip, W.-H. 1984, JGR, 89, 3829

References•••••••••••••••

Ip, W.-H. 1995, Icarus, 115, 295
Ip, W.-H., & Mendis, D. A. 1983, GeoRL, 10, 207
Ishihara, O. 2007, JPhD., 40, R121
Jones, G. H., Krupp, N., Kruger, H., et al. 2006, GeoRL, 33, L21202
Juhasz, A., & Horanyi, M. 2002, JGRA, 107, 1066
Jurac, S., Johnson, R. E., & Richardson, J. D., 2001, Icarus, 149, 384
Kempf, S., Beckmann, U., Srama, R., et al. 2006, P&SS, 54, 999
Krivov, A. V., & Banaszkiewicz, M. 2001, P&SS, 49, 1265
Lehtinen, N. G., Inan, U. S., & Bell, T. F., 2001, JGR, 106, 28841
Liao, C.-T., Teng, L.-W., Tsai, C.-Y., Io, C.-W., & I, L. 2008, PhRvL,100, 185004
Melzer, A., Kaeding, S., Block, D., & Piel, A. 2008, JPCM, 20, 4204
Mendis, D. A., & Axford, W. I. 1974, AREPS, 2, 419
Mendis, D. A., Hill, J. R., Houpis, H. L. F., et al. 1981, ApJ, 249, 787
Northrop, T. G., & Hill, J. R. 1983, JGR, 88, 6102
Nosenko, V., Avinash, K., Goree, J., & Liu, B. 2004, PhRvL, 92, 085001

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