Generation of auroral kilometric radiation in upper hybrid wave-lower hybrid soliton interaction

Journal Article · Sat Aug 01 00:00:00 EDT 1992 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JA00101· OSTI ID:6991659

Pottelette, R; Dubouloz, N ^[1]; Treumann, R A ^[2]

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1. Centre National d'Etudes des Telecommunications St. Maur des Fosses (France)
2. Max-Planck-Inst. fuer Physick und Astrophysik, Garching bei Muenchen (Germany)

Sporadic bursts of auroral kilometric radiation (AKR) associated with strong bursty electrostatic turbulence in the vicinity of the lower hybrid frequency have been frequently recorded in the AKR source region by the Viking satellite. The variation time scale of these emissions is typically 1 s, long enough for lower hybrid waves to grow to amplitudes of several hundred millivolts per meter and to evolve nonlinearly into solitons. On the basis on these observations it is suggested that formation of lower hybrid solitons may play a role in the generation of AKR. A theoretical model is proposed which is based on the direct acceleration of electrons in the combined lower hybrid soliton and upper hybrid wave fields. The solitons act as sporadic, localized antennas allowing for efficient conversions of the electrostatic energy stored in upper hybrid waves into electromagnetic radiation at a frequency above the X mode cutoff. Excitation of lower hybrid waves is due to the presence of energetic electron beams in the auroral zone found to be associated with steep plasma density gradients. Upper hybrid waves can be excited by a population of energetic electrons with loss cone distributions. The power of the electromagnetic radiation obtained is only noticeable in regions where the plasma frequency is less than the electron gyrofrequency. The theory predicts spectral power densities of the order of 10{sup {minus}11} to 10{sup {minus}9} W m{sup {minus}2} Hz{sup {minus}1} in the source region, in good agreement with the Viking observations. The sporadic nature of the radiation derives from lower hybrid soliton collapses which occur on {approximately}1-s time scales.

• OSTI ID: 6991659
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 97:A8; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCELERATION
AURORAL ZONES
DISTRIBUTION
ELECTRIC FIELDS
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
LEPTONS
LOSS CONE
MATHEMATICAL MODELS
PLASMA DENSITY
PLASMA WAVES
QUASI PARTICLES
RADIATIONS
RADIOWAVE RADIATION
SATELLITES
SOLITONS
SPATIAL DISTRIBUTION
TURBULENCE