Generation of ELF and VLF waves by HF Heater‐modulated polar electrojet via a thermal instability process

S. P. Kuo, M. C. Lee

Research output: Contribution to journalArticle

Abstract

Generation of ELF and VLF waves via a thermal instability process in a HF‐modulated polar electrojet has been investigated. It is shown that a positive feedback through the electron‐neutral collisional heating process can cause the transient response of the plasma to the modulated HF heater to grow exponentially. The threshold fields of the instability under normal electrojet conditions are found to be about 2.25 V / m and 1.13 V / m for the operation of the o‐mode and x‐mode heaters with a 50% duty cycle, respectively. For a heater wave field of, e.g., 1.5 V/m, the instability can be excited by the x‐mode heater within a few tens of millisecond. The predicted dependence of the ELF/VLF radiation amplitude on the percentage of the duty cycle of the HF modulation is identical to that of the recent observational results of Barr and Stubbe [1991b].

Original languageEnglish (US)
Pages (from-to)189-192
Number of pages4
JournalGeophysical Research Letters
Volume20
Issue number3
DOIs
StatePublished - Feb 5 1993

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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