Physics
Scientific paper
Dec 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002agufm.p11a0343s&link_type=abstract
American Geophysical Union, Fall Meeting 2002, abstract #P11A-0343
Physics
2780 Solar Wind Interactions With Unmagnetized Bodies, 5465 Rings And Dust, 5470 Surface Materials And Properties, 6015 Dust, 7831 Laboratory Studies
Scientific paper
There are many examples of active dust transport near surfaces in the solar system: dust grains suspended above the lunar surface, spokes observed in Saturn's rings, and recent images of infilled craters from the NEAR spacecraft at Eros. Electrostatic dust levitation and transport have also been theorized to occur on Mercury, asteroids, and comets. Dusty regoliths are produced by the interplanetary micrometeoroid flux on nearly all airless bodies in the solar system. Therefore, understanding dust charging, levitation, and dynamics above surfaces is important for interpreting remote sensing data and analyzing the evolution of most planetary surfaces. Objects in a plasma, such as planetary bodies in the solar wind, charge to a floating potential determined by the balance between charging currents in the local plasma environment. The primary charging currents are due to collection of electrons and ions from the plasma, photoemission, and secondary electron emission. When photoemission is the dominant charging process, a photoelectron sheath forms near the surface of the object. Positively charged particles released from the surface can levitate above the surface at a height where the gravitational force is balanced by the electric force. In cases where secondary electron emission and photoemission are weak, objects will become negatively charged due to electron collection and will be surrounded by a plasma sheath. Negatively charged dust grains from these surfaces can levitate in the electric field created by the plasma sheath. Dust levitation and transport near surfaces in the solar system is thought to be primarily due to the interaction between charged dust particles and a photoelectron or plasma sheath on the surface. We report the results of experiments on the levitation and transport of dust particles in an argon plasma sheath above a flat, conducting surface. Levitation experiments are performed using monodisperse polystyrene DVB microbeads. Transport experiments are performed using JSC-1, a lunar regolith simulant, and JSC-Mars-1, a martian regolith simulant. Plasma characteristics are determined using a Langmuir probe, while the sheath potential profiles are measured by an emissive probe. Dust particles levitating above the surface of the plate are illuminated by an Ar laser and observed by a video camera. Various types and sizes of particles can levitate above the plate, and particle dynamics in the plasma sheath can be quite complex. We find that particle levitation height and corresponding charge are comparable to the values calculated from orbital motion limited (OML) theory. We also derive an equation to describe the evolution of the dust distribution on the plate as a result of transport in the plasma sheath. In addition, we present results from a numerical model that simulates dust transport in a sheath above a planetary surface. This work is supported by NASA's Microgravity Fluid Physics Program and NASA's Office of Space Sciences GSRP.
Colwell Joshua E.
Horanyi Mihaly
Robertson Scott
Sickafoose Amanda A.
No associations
LandOfFree
Dust Levitation and Transport Near Surfaces does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Dust Levitation and Transport Near Surfaces, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dust Levitation and Transport Near Surfaces will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1891751