coherent generation of VLF hiss

Maggs, J. E.

doi:10.1029/ja081i010p01707

Cited by 226 publications

(180 citation statements)

References 27 publications

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“…In contrast to the purely electrostatic Langmuir waves well studied in past, analogous investigations in magnetized plasmas at oblique propagation, however, require the full apparatus of electromagnetic plasma dispersion theory and less work on this has appeared in the literature (see e.g. Kennel, 1966;Maggs, 1976;Lin et al, 1984;Morgan et al, 1994;Willes and Cairns, 2000;Kopf et al, 2010).…”

Section: Discussion and Summarymentioning

confidence: 99%

Whistler-Langmuir oscillitons and their relation to auroral hiss

Sauer

Sydora

2011

Ann. Geophys.

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Abstract.A new type of oscilliton (soliton with superimposed spatial oscillations) is described which arises in plasmas if the electron cyclotron frequency e is larger than the electron plasma frequency ω e , which is a typical situation for auroral regions in planetary magnetospheres. Both highfrequency modes of concern, the Langmuir and the whistler wave, are completely decoupled if they propagate parallel to the magnetic field. However, for oblique propagation two mixed modes are created with longitudinal and transverse electric field components. The lower mode (in the literature commonly called the whistler mode, e.g. Gurnett et al., 1983) has whistler wave characteristics at small wave numbers and asymptotically transforms into the Langmuir mode. As a consequence of the coupling between these two modes, with different phase velocity dependence, a maximum in phase velocity appears at finite wave number. The occurrence of such a particular point where phase and group velocity coincide creates the condition for the existence of a new type of oscillating nonlinear stationary structure, which we call the whistler-Langmuir (WL) oscilliton. After determining, by means of stationary dispersion theory, the parameter regime in which WL oscillitons exist, their spatial profiles are calculated within the framework of cold (non-relativistic) fluid theory. Particle-in-cell (PIC) simulations are used to demonstrate the formation of WL oscillitons which seem to play an important role in understanding electron beam-excited plasma radiation that is observed as auroral hiss in planetary magnetospheres far away from the source region.

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Section: Discussion and Summarymentioning

confidence: 99%

Whistler-Langmuir oscillitons and their relation to auroral hiss

Sauer

Sydora

2011

Ann. Geophys.

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“…[30] The second panel in Figure 8 shows the VLF activity throughout the flight, indicating, through coherent generation of whistler mode VLF hiss, the large-scale electron precipitation [Maggs, 1976]. There was strong VLF hiss throughout T + 0 to T + 450s, when the rocket flew through the 3 large arcs seen in the all-sky and Polar images.…”

Section: Flight Surveymentioning

confidence: 99%

Multipoint measurements of field‐aligned current density in the auroral zone

et al. 2003

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[1] In this paper we present the analysis and interpretation of a multipoint observation of magnetic field structures at the poleward edge of a premidnight auroral arc by the Enstrophy sounding rocket mission. Four Free-Flying Magnetometers (FFMs) employing autonomous nanospacecraft technology were deployed from the main payload during the flight, and multipoint magnetic field measurements were made. Signatures consistent with both spatial and temporal interpretations were found to be present when large fluctuations in B were seen at the edge of an arc as the rocket flew into the polar cap. Reasons for the interpretation of spatial or temporal features are given and supported by a simple model of multiple payloads crossing through several moving current sheets and a study of the fine structure of this auroral event using multipoint, correlative wavelet analysis to find velocities of structures at different scale sizes. We show that the direct measurement method of current density using multipoint measurement of magnetic fields gives us a different current density than what would be inferred from a single-point measurement and that the multipoint measurement also provides an inherent check on the validity of the measurement through a calculation of the divergence of the measured B.INDEX TERMS:

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“…Hence when the S3 and S4 baselines imply smaller electric fields compared to the 34 baseline, the wavelengths must be less than roughly 30 m. Above the lower hybrid frequency (8 kHz at 266 s and 6 kHz at 406 s), plasma waves often become short wavelength when auroral hiss propagates onto the lower hybrid resonance cone [Maggs, 1976;Paschmann, 2002], which explains why the baselines imply different electric fields at higher frequencies. However the situation below 5 kHz is different.…”

Section: In Situ Datamentioning

confidence: 99%

SERSIO: Svalbard EISCAT Rocket Study of Ion Outflows

et al. 2007

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[1] The SERSIO sounding rocket was launched from Ny-Alesund, Svalbard, into a type 2 ion upflow event simultaneously observed by the European Incoherent Scatter (EISCAT) radar facility in Longyearbyen on 22 January 2004 at 0857 UT. It reached an apogee of 782 km. In situ wave data and thermal particle measurements in the cusp/cleft region clearly show core thermal ion temperature enhancements up to 0.8 eV in association with 0-4 kHz broadband extremely low frequency wave activity (BBELF). The in situ observation of wave heating in the cusp/cleft region at these low altitudes (520-780 km) and high densities (80,000/cm 3 ) is an important measurement and should be included in any model of ion energization. Wave activity in the form of naturally enhanced ion acoustic lines (NEIAL) was seen by the EISCAT radar in the same activity region. Periods of NEIAL were compared with in situ auroral electron data that show no evidence of a bump-on-tail distribution; thus our data do not support using Langmuir turbulence to explain these radar echoes. In contrast, these observations associating NEIAL with BBELF activity suggest that they may be the same phenomenon. During these comparisons, all-sky camera images were used to verify similar environmental conditions between the rocket and radar measurement volumes, while the spatial separation between the volumes was less than 500 km. In situ measurements also confirm the link between soft electron precipitation and thermal electron temperature enhancements in this ion upflow environment.

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coherent generation of VLF hiss

Cited by 226 publications

References 27 publications

Whistler-Langmuir oscillitons and their relation to auroral hiss

Whistler-Langmuir oscillitons and their relation to auroral hiss

Multipoint measurements of field‐aligned current density in the auroral zone

SERSIO: Svalbard EISCAT Rocket Study of Ion Outflows

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