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A comparison of intense electrostatic waves near f UHR with linear instability theory
Author(s) -
Kurth W. S.,
AshourAbdalla M.,
Frank L. A.,
Kennel C. F.,
Gurnett D. A.,
Sentman D. D.,
Burek B. G.
Publication year - 1979
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl006i006p00487
Subject(s) - plasmasphere , magnetosphere , physics , lower hybrid oscillation , instability , resonance (particle physics) , cyclotron resonance , harmonic , computational physics , atomic physics , cyclotron , plasma oscillation , plasma , geophysics , nuclear physics , mechanics , quantum mechanics
Intense electrostatic waves beyond the plasmapause have recently been identified at frequencies near the upper hybrid resonance frequency. In addition, the waves occur within a band at an odd, half‐harmonic of the local electron gyrofrequency. These bands of electrostatic turbulence are among the most intense waves detected within the earth’s magnetosphere. Measurements obtained with the ISEE 1 plasma wave receiver show that the intense waves appear to be intensifications of an electrostatic cyclotron harmonic band near the upper hybrid resonance frequency. A straightforward explanation of intense waves at the upper hybrid resonance frequency exists in the electrostatic multi‐cyclotron emission theory. For a broad range of plasma parameters nonconvective instability or large spatial growth rates occur within the cyclotron band encompassing the cold upper hybrid frequency. Comparison of spatial growth rate spectra with measured wave spectra shows that there is excellent qualitative agreement between the linear theory and the observed wave characteristics.