Fluctuations of the charge on a dust grain in a plasma

Journal Article · Fri Apr 01 00:00:00 EST 1994 · IEEE Transactions on Plasma Science (Institute of Electrical and Electronics Engineers); (United States)

OSTI ID:7296322

Cui, C; Goree, J ^[1]

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1. Univ. of Iowa, Iowa City, IA (United States). Dept. of Physics

A dust grain in a plasma acquires an electric charge by collecting electron and ion currents. These currents consist of discrete charges, causing the charge to fluctuate around an equilibrium value (Q). Electrons and ions are collected at random intervals and in a random sequence, with probabilities that depend on the grain's potential. The authors developed a model for these probabilities and implemented it in a numerical simulation of the collection of individual ions and electrons, yielding a time series Q(t) for the grain's charge. Electron emission from the grain is not included, although it could be added easily to the method. They obtained the power spectrum and the rms fluctuation level, as well as the distribution function of the charge. Most of the power in the spectrum lies at frequencies much lower than 1/[tau], the inverse charging time. The rms fractional fluctuation level varies as 0.5 [vert bar][l angle]N[r angle][vert bar][sup [minus]1/2], where [l angle]N[r angle] = [l angle]Q[r angle]/e is the average number of electron charges on the grain. This inverse square-root scaling means that fluctuations are most important for small grains. They also show that very small grains can experience fluctuations to neutral and positive polarities, even in the absence of electron emission.

• OSTI ID: 7296322
• Journal Information: IEEE Transactions on Plasma Science (Institute of Electrical and Electronics Engineers); (United States), Vol. 22:2; ISSN 0093-3813
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC DUST
CHARGE COLLECTION
EARTH MAGNETOSPHERE
COMPUTERIZED SIMULATION
ELECTRIC CHARGES
PLASMA
THEORETICAL DATA
TIME-SERIES ANALYSIS
DATA
DUSTS
EARTH ATMOSPHERE
INFORMATION
MATHEMATICS
NUMERICAL DATA
SIMULATION
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