On the generation of a broad downshifted spectrum of HF wave enhanced plasma lines in the ionospheric heating experiments

S. P. Kuo, M. C. Lee

Research output: Contribution to journalArticle

Abstract

Generation of a broad downshifted spectrum of HF wave enhanced plasma Lines (HFPLs) in ionospheric heating experiments is explored. Langmuir waves are first excited within a cone around the geomagnetic field by the HF wave, in the region near its reflection height, through the oscillating two stream instability (OTSI). These Langmuir waves then cascade through a secondary parametric instability, whereby an obliquely propagating Langmuir pump wave decays into an obliquely propagating Langmuir sideband and a lower hybrid decay mode, which propagates in a direction perpendicular to the Langmuir pump wave. The excited Langmuir sidebands have a broad downshifted frequency spectrum and large propagation angles. Their propagation angles are further widened via the filamentation instability or scattering off short-scale field-aligned density irregularities. Thus they become detectable by backscatter radars as HFPLs with a broad downshifted frequency spectrum. The results of our analysis show that it requires HF field amplitude of 3.6 V/m to cascade the OTSI-excited Langmuir waves, for example, 8 times to produce a downshifted spectral width of 50 KHz in the Arecibo heating experiments.

Original languageEnglish (US)
Pages (from-to)3289-3292
Number of pages4
JournalGeophysical Research Letters
Volume26
Issue number21
DOIs
StatePublished - Nov 1 1999

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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