Pulsed currents carried by whistlers. II. Excitation by biased electrodes

Journal Article · Sun May 01 00:00:00 EDT 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870692· OSTI ID:6930646

Urrutia, J M; Stenzel, R L; Rousculp, C L ^[1]

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1. University of California, Los Angeles, California 90024-1547 (United States)

The transport of time-dependent current between electrodes in contact with a large laboratory magnetoplasma is examined experimentally. Single electrodes biased with respect to the chamber wall or pairs of electrically floating electrodes are used to produce pulsed currents ([omega][sub [ital ci]][much lt]2[pi]/[Delta][ital t][much lt][omega][sub [ital ce]]). The associated magnetic field vector, [bold B]([bold r],[ital t]), is measured in space and time, and the total current density is calculated from [bold J]([bold r],[ital t])=[del][times][bold B]([bold r],[ital t])/[mu][sub 0]. The current front is found to propagate at a characteristic wave speed, which does not depend on current amplitude or polarity. The transient current spreads across [bold B][sub 0] within a conical region, which depends on source geometry and plasma parameters. It is shown by Fourier transforming [bold B]([bold r],[ital t]) into [bold B]([bold k],[omega]) that the transient fields consist of a spectrum of oblique low-frequency whistler waves. In Fourier space, the inductive and space charge electric fields are calculated from Faraday's law and the assumption that [bold E][sub tot]=[bold E][sub ind]+[bold E][sub sc] along [bold B][sub 0] is negligible. Inverse transforming yields [bold E]([bold r],[ital t]). The transient wave fields ([bold B],[bold J],[bold E]) exhibit multiple induction effects and the formation of space charges. The results are relevant to pulsed Langmuir probes, beams, and antennas as well as moving steady-state magnetic/current sources such as particle collectors on spacecraft and magnetized asteroids (e.g., Gaspra).

• OSTI ID: 6930646
• Journal Information: Physics of Plasmas; (United States), Journal Name: Physics of Plasmas; (United States) Vol. 1:5; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700330* -- Plasma Kinetics
Transport
& Impurities-- (1992-)
700340 -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
ASTEROIDS
CURRENT DENSITY
ELECTRIC PROBES
ELECTRODES
ELECTROMAGNETIC RADIATION
FARADAY LAWS
FLUID MECHANICS
FOURIER ANALYSIS
HYDRODYNAMICS
LANGMUIR PROBE
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MECHANICS
NOISE
PROBES
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
TRANSIENTS
WHISTLERS