Cyclotron harmonic waves in warm plasmas

Crawford, F. W.

doi:10.6028/jres.069d.086

Cited by 39 publications

(45 citation statements)

References 28 publications

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“…The emission at F uh is seen as unstable on the second passive spectrum. harmonic branch after that time when 2F c < F uh < 3 F c. This could be due to the fact that F uh and F q are very close in frequency, which can happen for some given Fp/F c ratios (Crawford, 1964). It is then difficult to clearly separate them with the frequency resolution of Whisper (160 Hz).…”

Section: Observationsmentioning

confidence: 99%

Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

et al. 2001

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Abstract. We use the data collected by the Whisper instrument onboard the Cluster spacecraft for a first test of its capabilities in the identification of the natural plasma waves observed in the Earth' s magnetosphere. The main signatures observed at the plasma frequency, upper hybrid frequency, and electron Bernstein modes were often difficult to be reliably recognized on previous missions. We use here the characteristic frequencies provided by the resonances triggered by the relaxation sounder of Whisper to identify with good confidence the various signatures detected in the complex wave spectra collected close to the plasmapause. Coupled with the good sensitivity, frequency and time resolution of Whisper, the resonances detected by the sounder allow one to precisely spot these natural emissions. This first analysis seems to confirm the interpretation of Geos observations: the natural emissions observed in Bernstein modes above the plasma frequency, now widely observed onboard Cluster, are not modeled by a single Maxwellian electrons distribution function. Therefore, multi-temperature electron distribution functions should be considered.

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Section: Observationsmentioning

confidence: 99%

Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

et al. 2001

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“…This approach considered both the D1 resonance and the 3/2 fce magnetospheric emission in terms of the same plasma wave instability of electrostatic ECH waves in the frequency region below the upper hybrid frequency band, i.e., where the dispersion curves cover the entire range between nfc e harmonics and have shapes similar to the one in the band labeled low band 1 in Figure 2 (more bands of this type appear as O)pe/O)ce increases [Crawford, 1965] The Qn emissions were attributed to an incoherent process involving a near-Maxwellian plasma distribution with a small population of non thermal high-energy electrons. They stressed that the "(n + 1/2)fce" emissions observed below fuh were likely due to a different mechanism.…”

Section: Introductionmentioning

confidence: 99%

An interpretation of banded magnetospheric radio emissions

Benson¹,

Osherovich²,

Fainberg³

et al. 2001

J. Geophys. Res.

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Abstract. Recently published Active Magnetospheric Particle Tracer Explorers/Ion Release Module (AMPTE/IRM) banded magnetospheric emissions, commonly referred to as "(n + 1/2)fee" emissions, where fee is the electron gyrofrequency, are analyzed by treating them as analogous to sounder-stimulated ionospheric emissions. We show that both individual spectra of magnetospheric banded emissions and a statistically derived spectra observed over the 2-year lifetime of the mission can be interpreted in a self-consistent manner. The analysis, which predicts all spectral peaks within 4% of the observed peaks, interprets the higher-frequency emissions as due to low group velocity Bernsteinmode waves and interprets the lower-frequency emissions as eigenmodes of cylindrical-electromagnetic plasma oscillations. The demarcation between these two classes of emissions is the electron plasma frequency fpe where an emission is often observed. This fpe emission is not necessarily the strongest. None of the observed banded emissions were attributed to the upper hybrid frequency. We present Alouette 2 and ISIS 1 plasma resonance data and model electron temperature (Te) values to support the argument that the frequency spectrum of ionospheric sounder-stimulated emissions is not strongly temperature dependent and thus that the interpretation of these emissions in the ionosphere is relevant to other plasmas (such as the magnetosphere) where N e and T e can be quite different but where the ratio fpe/fee is identical. The N e values deduced from the spectral interpretation do not agree with the values determined from the AMPTEB_RM three-dimensional plasma instrument. The latter, which represent a lower •ound, are found to be higher than the former by a factor of 3.2 -3.5. All values were less than 1 cm-, a domain known for measurement difficulties. One possible explanation is that the wave and plasma techniques respond to different components of a non-Maxwellian magnetospheric electron distribution.

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“…This long duration of the electrostatic resonance is partly resulted by the collisionless and non Maxwellian plasma in the magnetosphere, and is partly resulted by the matching of the wavelength, with the antenna length. The characteristic wavelength of the electrostatic wave is in a range (STIX, 1962;CRAWFORD, 1965;OYA, 1971a), as (5) When the temperature 10 eV is selected, the wavelength is in a range very close to the antenna length 102 m from tip to tip.…”

Section: Plasma Resonancementioning

confidence: 99%

“…The principal resonances such as the upper hybrid resonance, the harmonics of the electron cyclotron resonance, and the plasma resonances have been interpreted in term of the matching concept of the moving vehicle with the propagating electrostatic plasma waves. The concept has initially been presented by CRAWFORD (1965) and also investigated in detail by FEJER and CALVERT (1964). The effect also has been checked by data analyses on Alouette 2 (BENSON, 1972).…”

Section: Introductionmentioning

confidence: 99%

Stimulation of plasma waves in the magnetosphere using satellite JIKIKEN (EXOS-B). Part I. Observation of plasma resonances.

Oya

Ono

Kamada

1981

J. geomagn. geoelec

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The stimulated plasma wave experiment (SPW) has been successfully carried out in the plasmasphere and the magnetosphere along the JIKIKEN (EXOS-B) satellite orbit where the plasma parameters indicate wide variety of the combination of the electron number density ranging from 1/cc to 104/cc, and the electron cyclotron frequency ranging from 6 kHz to 200 kHz.The observed plasma resonances are: i) the upper hybrid resonance FIIHR, ii) the plasma resonance FP, iii) the higher harmonics of the electron cyclotron resonance nFH, iv) the electrostatic resonance FQn, and v) the of the diffuse resonance FDn. The upper hybrid resonances usually persists for long periods up to 125 msec and the electron cyclotron resonances are stimulated at frequency with the very high harmonic number n; sometimes, the nFH resonance takes place for n>30.The detection of the plasma resonance FP is more difficult compared with the case of the observation of the FIIHR resonance due to the expanded wavelength of the electrostatic plasma waves near at FP. The observation of the diffuse resonances is the most difficult case in the magnetosphere since the energy of the plasma in the magnetosphere overcomes the electric field intensity generated by the SPW pulse transmission. All the features of the resonances reflect the characteristics of the magnetospheric plasma that contains the energetic and non-Maxwellian components of the particles. The measurement of the plasma resonance contributes to the detection of the local electron density, magnetic field intensity; conditions for the wave particle interactions are also analyzed from the duration features of the plasma resonances.

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Cyclotron harmonic waves in warm plasmas

Cited by 39 publications

References 28 publications

Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

An interpretation of banded magnetospheric radio emissions

Stimulation of plasma waves in the magnetosphere using satellite JIKIKEN (EXOS-B). Part I. Observation of plasma resonances.

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