Pulsed currents carried by whistlers. Part I: Excitation by magnetic antennas

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Physics of Fluids B; (United States)

DOI:https://doi.org/10.1063/1.860517· OSTI ID:7118370

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

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

Time-varying plasma currents associated with low-frequency whistlers have been investigated experimentally. Pulsed currents are induced in the uniform, boundary-free interior of a large laboratory plasma by means of insulated magnetic antennas. The time-varying magnetic field is measured in three dimensions and the current density is calculated from [del][times][bold B]([bold r],[ital t])=[mu][sub 0][bold J], where [bold J] includes the displacement current density. Typical fields [ital B]([bold r],[ital t]) and [bold J]([bold r],[ital t]) induced by a magnetic loop antenna show three-dimensional helices due to linked toroidal and solenoidal field topologies. Constant amplitude and phase surfaces assume conical shapes since the propagation speed along [bold B][sub 0] is higher than oblique to [bold B][sub 0]. The wave vector is highly oblique to [bold B][sub 0] while the energy flow is mainly along [bold B][sub 0]. The electric field in the wave packet contains both inductive and space-charge contributions, the latter arising from the different dynamics of electrons and ions as explained by physical arguments. The dominant electric field in a whistler packet is a radial space-charge field. Neither the field topology nor the propagation characteristics are sensitive to the induced magnetic field amplitude up to [ital B][sub wave][approx lt][ital B][sub 0]. The results are relevant to both the basic properties of whistlers and to applications such as large loop antennas and electrodynamic tethers in space plasmas.

• OSTI ID: 7118370
• Journal Information: Physics of Fluids B; (United States), Journal Name: Physics of Fluids B; (United States) Vol. 5:2; ISSN 0899-8221; ISSN PFBPEI
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700340 -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
700350* -- Plasma Production
Heating
Current Drive
& Interactions-- (1992-)
ANTENNAS
CURRENT DENSITY
ELECTRICAL EQUIPMENT
ELECTROMAGNETIC RADIATION
ENERGY-LEVEL TRANSITIONS
EQUIPMENT
EXCITATION
MAGNETIC FIELDS
MATHEMATICS
NOISE
PULSES
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
TOPOLOGY
WHISTLERS