Low frequency continuum as observed in the solar wind from ISSE 3: Thermal electrostatic noise

Journal Article · Tue Jul 01 04:00:00 EDT 1980 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA085iA07p03419· OSTI ID:5053071

Hoang, S; Steinberg, J; Epstein, G; Tilloles, P; Fainberg, J; Stone, R G

The low-frequency (LF) continuum, observed in the solar wind by ISSE 3, is shown to be generated by local electrostatic (thermal) plasma waves and not by electromagnetic waves. The continuum has been investigated between 30 and 200 kHz utilizing the radio astronomy receivers and antennas aboard ISEE 3. This experiment has noise level 5--20 dB lower than that of previous system, as well as continuous frequency coverage from 30 to 80 kHz. Not only is the spacecraft itself very quiet but also it is stationed far from terrestrial noise sources. The spin plane wire antenna has a smaller photoemitting area and is consequently less noisy than tubular type antennas previously used.of is not observed only when it happens to fall outside the receiver frequency range. The noise voltage variations as a function of f/sub p/ are deduced from observations of the 2f/sub p/ line. The observed noise levels are in close agreement with those obtained by Imp 6 and 8 at locations nearer the earth, thus ruling out a magnetospheric origin. The phenomenon is interpreted as local thermal plasma noise. The antenna radiation resistance in the plasma electrostatic mode can be computed and then used to determine the noise. Theory shows, for example, that for f>>f/sub p/ the S antenna spectrum is f/sub p//sup 2//f/sup 3/ provided that the electron density N/sub e/ is sufficiently large that the antenna is longer than 7 Debye lengths. In general, the theoretical results for f>f are in excellent agreement with observations. Previous observations are reviewed to show that many of them, postulating a magnetospheric radio source, can be better interpreted instead with the mechanism outlined in the present paper.

• Research Organization: Departement de Recherches Spatiales, (Laboratoire Associe au CNRS No 264) Observatoire de Paris, 92190 Meudon, France
• OSTI ID: 5053071
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 85:A7; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTROMAGNETIC RADIATION
ELECTRON DENSITY
FREQUENCY RANGE
FUNCTIONS
KHZ RANGE
NOISE
PLASMA WAVES
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
SOLAR ACTIVITY
SOLAR WIND
SPECTRAL DENSITY
SPECTRAL FUNCTIONS