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Electrostatic electron cyclotron harmonic (ESCH) echoes found near the plasmapause by the EXOS‐B (Jikiken) satellite
Author(s) -
Ono Takayuki,
Oya Hiroshi
Publication year - 1988
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/gl015i002p00156
Subject(s) - plasmasphere , magnetosphere , physics , plasma , atomic physics , dispersion relation , electron , plasma oscillation , electron density , harmonic , waves in plasmas , optics , quantum mechanics
A stimulated plasma wave experiment by the EXOS‐B satellite showed the appearance of echoes of plasma waves with a delay time of several msec. We examined the frequency dependence of the echoes in comparison with the observed plasma resonances and the dispersion relation of plasma waves. The propagation mode of the echoes was identified as the electrostatic electron cyclotron harmonic (ESCH) waves. The appearance regions were examined with respect to the electron density profiles in the magnetosphere that have been determined by measuring the frequencies of stimulated plasma resonances. The ESCH echoes are frequently observed in a detached plasma region. Near the plasmapause the appearance of echoes is significantly frequent in regions where the plasma density is rapidly increasing in the plasmasphere due to a strong supply from the ionsphere. Because of their propagation mode and the state of the plasma density profiles in their appearance regions in the magnetosphere, the echoes are inferred to be produced by the reflection of propagating ESCH waves from small‐scale density irregularities of environmental plasma.