Dusty Plasmas in the Laboratory and Space Bob Merlino April 2003 APS Meeting Philadelphia, PA

Outline 1)Introduction – what is a dusty plasma and where are they found 2)the charging of dust in a plasma 3)devices for producing dusty plasmas 4)waves in dusty plasmas

plasma = electrons + ions What is a dusty plasma? Debye shielding small particle of solid matter becomes negatively charged absorbs electrons and ions

Dusty Plasma in the Universe Dust represents much of the solid matter in the universe and this component often coexists with the ionized matter forming a dusty plasma.

Importance of Charged Dust  the dust acquires an electrical charge and thus is subject to electromagnetic as well as gravitational forces  the charged dust particles participate in the collective plasma processes

DUSTY PLASMAS Solar nebula planetary rings interstellar medium comet tails noctilucent clouds lightning Microelectronic processing rocket exhaust fusion devices NaturalMan-made

Our solar system accumulated out of a dense cloud of gas and dust, forming everything that is now part of our world. Rosette Nebula

Noctilucent Clouds (NLC) Occur in the summer polar mesosphere (~ 82 km) 50 nm ice crystals Associated with unusual radar echoes and reductions in the local ionospheric density

An early temperature measurement in a dusty plasma. A flame is a very weakly ionized plasma that contains soot particles.

Comet Hale-Bopp

Spokes in Saturn’s B Ring Voyager 2 Nov Cassini- Huygens July 2004

Semiconductor Processing System dust silane (SiH 4 ) + Ar + O 2  SiO 2 particles

Semiconductor Manufacturing dust Si

Physics Today August 1994

Dust Charging Processes electron and ion collection secondary emission UV induced photoelectron emission Total current to a grain = 0  I = I e + I i + I sec + I pe = 0

electron repulsion ion enhancement The Charge on a Dust Grain In typical lab plasmas I sec = I pe = 0 Electron thermal speed >> ion thermal speed so the grains charge to a negative potential V S relative to the plasma, until the condition I e = I i is achieved. a Q = (4  o a) V S

Typical Lab Plasma For T e = T i = T in a hydrogen plasma V S =  2.5 (kT/e) If T  1 eV and a = 1  m, Q   2000 e Mass m  5  m p

Dust Charge Measurements Electron Energy (eV) Glass Graphite Walch, Horanyi, & Robertson, Phys. Rev. Lett. 75, 838 (1995)

Devices for producing dusty plasmas

RF Dusty Plasma Devices

Equipotential profiles of an anode double layer anode Device for studying the trapping of dust in a dc glow discharge

DUST IN A GLOW DISCHARGE N2N2 Vacuum vessel PS + B Anode Dust Tray Anode Glow Plasma Dust: kaolin (aluminum silicate) E mg QE

wavefronts Dust Acoustic Wave Image

dust mass DA Dispersion relation Monochromatic plane wave solutions for T e = T i = T where  = n do /n +o

Dust Acoustic Wave Dispersion Relation theory

Shocks in Dusty Plasma

Shocks in Dusty Plasma- results

Shocks in dusty plasmas Conclusions Ion acoustic compress- ional pulses are observed to steepen as they travel through a dusty plasma Relevant to astrophysical contexts where density disturbances travel through dust clouds

Conclusions and Outlook Only recently have we begun to explore the behavior of dusty plasmas in the laboratory -charging mechanisms, waves Technological applications of dusty plasmas are now being exploited - ceramic deposition – composites - growth of nanosize particles -diamond growth and deposition on metals

Dusty plasmas in space are usually embedded in magnetic fields. This aspect of dusty plasmas has yet to be studied in the lab R = Mv/QB >> typical lab plasmas Coulomb CrystalsDusty plasmas may form strongly coupled systems known as Coulomb Crystals – a new area for plasma physics research

Dusty Plasma DUST

RF Dusty Plasma Device