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Deterministic chaos in modulated multi-cell drifts of localized lower-hybrid oscillations excited by high-frequency waves in the ionosphere.

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Title: Deterministic chaos in modulated multi-cell drifts of localized lower-hybrid oscillations excited by high-frequency waves in the ionosphere.
Authors: Leyser, Thomas B.1 (AUTHOR) thomas.leyser@irfu.se
Source: Annales Geophysicae (ANGEO) (09927689). 2025, Vol. 43 Issue 1, p319-329. 11p.
Subject Terms: *Geomagnetism, *Shortwave radio, *Electromagnetic interactions, *Radio waves, *Frequency spectra
Abstract: The prominent broad upshifted maximum (BUM) feature in electromagnetic emissions stimulated by powerful high-frequency radio waves in the ionosphere exhibits an exponential spectrum for pump frequencies near a harmonic of the ionospheric electron gyro frequency. Exponential power spectra are a characteristic of deterministic chaos. In the present treatment, a two-fluid model is derived for lower-hybrid (LH) oscillations driven by parametric interaction of the electromagnetic pump field, the electron Bernstein mode, and the upper-hybrid mode, as previously proposed to interpret the BUM. In two-dimensional geometry across the geomagnetic field, LH oscillations localized in cylindrical density depletions are associated with multi-cell plasma drift patterns. The numerical simulations show that topological modulations of the drift can give rise to approximately Lorentzian-shaped pulses in the LH time signal. For parameter values typical of the ionospheric experiments, the exponential power spectrum of the Lorentzian pulses has a slope that is consistent with the slope of the BUM spectrum. The BUM spectral structure is therefore attributed to deterministic chaos in LH dynamics. [ABSTRACT FROM AUTHOR]
Database: Energy & Power Source
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Header DbId: enr
DbLabel: Energy & Power Source
An: 186648675
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PubTypeId: academicJournal
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  Label: Title
  Group: Ti
  Data: Deterministic chaos in modulated multi-cell drifts of localized lower-hybrid oscillations excited by high-frequency waves in the ionosphere.
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  Data: <searchLink fieldCode="AR" term="%22Leyser%2C+Thomas B%2E%22">Leyser, Thomas B.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> thomas.leyser@irfu.se</i>
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  Data: <searchLink fieldCode="JN" term="%22Annales+Geophysicae+%28ANGEO%29+%2809927689%29%22">Annales Geophysicae (ANGEO) (09927689)</searchLink>. 2025, Vol. 43 Issue 1, p319-329. 11p.
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  Data: *<searchLink fieldCode="DE" term="%22Geomagnetism%22">Geomagnetism</searchLink><br />*<searchLink fieldCode="DE" term="%22Shortwave+radio%22">Shortwave radio</searchLink><br />*<searchLink fieldCode="DE" term="%22Electromagnetic+interactions%22">Electromagnetic interactions</searchLink><br />*<searchLink fieldCode="DE" term="%22Radio+waves%22">Radio waves</searchLink><br />*<searchLink fieldCode="DE" term="%22Frequency+spectra%22">Frequency spectra</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: The prominent broad upshifted maximum (BUM) feature in electromagnetic emissions stimulated by powerful high-frequency radio waves in the ionosphere exhibits an exponential spectrum for pump frequencies near a harmonic of the ionospheric electron gyro frequency. Exponential power spectra are a characteristic of deterministic chaos. In the present treatment, a two-fluid model is derived for lower-hybrid (LH) oscillations driven by parametric interaction of the electromagnetic pump field, the electron Bernstein mode, and the upper-hybrid mode, as previously proposed to interpret the BUM. In two-dimensional geometry across the geomagnetic field, LH oscillations localized in cylindrical density depletions are associated with multi-cell plasma drift patterns. The numerical simulations show that topological modulations of the drift can give rise to approximately Lorentzian-shaped pulses in the LH time signal. For parameter values typical of the ionospheric experiments, the exponential power spectrum of the Lorentzian pulses has a slope that is consistent with the slope of the BUM spectrum. The BUM spectral structure is therefore attributed to deterministic chaos in LH dynamics. [ABSTRACT FROM AUTHOR]
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=enr&AN=186648675
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      – Type: doi
        Value: 10.5194/angeo-43-319-2025
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      – Code: eng
        Text: English
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      – SubjectFull: Geomagnetism
        Type: general
      – SubjectFull: Shortwave radio
        Type: general
      – SubjectFull: Electromagnetic interactions
        Type: general
      – SubjectFull: Radio waves
        Type: general
      – SubjectFull: Frequency spectra
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      – TitleFull: Deterministic chaos in modulated multi-cell drifts of localized lower-hybrid oscillations excited by high-frequency waves in the ionosphere.
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              Text: 2025
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