On the stability of obliquely propagating whistlers

Brinca, A. L.

doi:10.1029/ja077i019p03495

Cited by 74 publications

(82 citation statements)

References 16 publications

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“…Whether the wave is damped or amplified depends on the electron distribution function and on the net results of all resonances. The stability of obliquely propagating whistlers was discussed, for example, by Brinca (1972).…”

Section: Discussion Observations and General Remarksmentioning

confidence: 99%

Propagation of whistler-mode chorus to low altitudes: divergent ray trajectories and ground accessibility

2005

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Abstract. We investigate the ray trajectories of nonductedly propagating lower-band chorus waves with respect to their initial angle θ 0 , between the wave vector and ambient magnetic field. Although we consider a wide range of initial angles θ 0 , in order to be consistent with recent satellite observations, we pay special attention to the intervals of initial angles θ 0 , for which the waves propagate along the field lines in the source region, i.e. we mainly focus on waves generated with θ 0 within an interval close to 0 • and on waves generated within an interval close to the Gendrin angle. We demonstrate that the ray trajectories of waves generated within an interval close to the Gendrin angle with a wave vector directed towards the lower L-shells (to the Earth) significantly diverge at the frequencies typical for the lower-band chorus. Some of these diverging trajectories reach the topside ionosphere having θ close to 0 • ; thus, a part of the energy may leak to the ground at higher altitudes where the field lines have a nearly vertical direction. The waves generated with different initial angles are reflected. A small variation of the initial wave normal angle thus very dramatically changes the behaviour of the resulting ray. Although our approach is rather theoretical, based on the ray tracing simulation, we show that the initial angle θ 0 of the waves reaching the ionosphere (possibly ground) is surprisingly close -differs just by several degrees from the initial angles which fits the observation of magnetospherically reflected chorus revealed by CLUSTER satellites. We also mention observations of diverging trajectories on low altitude satellites.

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Section: Discussion Observations and General Remarksmentioning

confidence: 99%

Propagation of whistler-mode chorus to low altitudes: divergent ray trajectories and ground accessibility

2005

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“…For example, Figure 3a shows the propagation of a single ray in the meridional plane, injected at L = 4.45, l = 0°, y = 0°, and f = 0.3 f ce . In the course of the ray propagation, the appropriate suprathermal distribution f (v) is used to calculate the Landau damping rate at every point along the ray path [Brinca, 1972;Bortnik et al, 2003], and integrated to give the total damping of the ray. Figure 3b shows the total damping calculated for the ray in panel (a), using the corresponding distribution illustrated in Figure 2b (solid line) as a function of group time, together with the latitude of the ray (dashed line).…”

Section: Ray Tracing Methodologymentioning

confidence: 99%

Modeling the propagation characteristics of chorus using CRRES suprathermal electron fluxes

2007

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[1] In the present paper, phase space density functions of the form f (v) = A N /v n are fitted to statistical distributions of suprathermal electron fluxes (E = 0.213-16.5 keV) from the CRRES satellite, parameterized by L-shell, Magnetic Local Time (MLT), and geomagnetic activity. The fitted distributions are used in conjunction with ray tracing to calculate the Landau damping rates of an ensemble of rays representing whistler-mode chorus waves. The modeled propagation characteristics are compared with observations of chorus wave power from the CRRES satellite, as a function of L-shell, MLT, and magnetic latitude, in various frequency bands, and under various geomagnetic conditions. It is shown that the model results are remarkably consistent with many aspects of the observed wave distributions, including frequency, L-shell, MLT, and latitudinal dependence. In addition, the MLT distribution of wave power becomes characteristically asymmetric during active geomagnetic conditions, with small propagation lengths on the nightside which increase with MLT and maximize on the dayside. This asymmetry is shown to be directly related to the dynamics of the Landau resonant suprathermal electrons which drift around the Earth whilst undergoing scattering and loss due to a variety of plasma waves. Consequently, the suprathermal electrons play an important role in radiation belt dynamics, by controlling the distribution of chorus, which in turn contributes to the acceleration and loss of relativistic electrons in the recovery phase of storms.

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“…[Inan and Bell, 1977]. The effects of Landau damping were included, using the theoretical formulation of Brinca [1972] in conjunction with typical suprathermal electron distributions observed by the HYDRA instrument on the Polar space craft . Each ray was traced until its amplitude was reduced by 3 dB due to Landau damping, after which time it was assumed that the wave-induced precipitation due to the remaining wave energy was negligible.…”

Section: Significance Of the Drift Loss Conementioning

confidence: 99%

Lightning‐induced energetic electron flux enhancements in the drift loss cone

Blake¹,

Inan²,

Walt³

et al. 2001

J. Geophys. Res.

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Abstract. With its relatively low altitude (520 x 670 km) orbit, SAMPEX is mostly below the stable trapping region where charged particles repeatedly drift around the Earth, especially at midlatitudes. Recent analyses of SAMPEX data have revealed a surprisingly common set of observations of enhanced energetic (>150 keV) electron fluxes at L < 3, during times when SAMPEX was located such that any electrons that it observed were in the drift loss cone (and were thus destined to be precipitated upon reaching

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On the stability of obliquely propagating whistlers

Cited by 74 publications

References 16 publications

Propagation of whistler-mode chorus to low altitudes: divergent ray trajectories and ground accessibility

Propagation of whistler-mode chorus to low altitudes: divergent ray trajectories and ground accessibility

Modeling the propagation characteristics of chorus using CRRES suprathermal electron fluxes

Lightning‐induced energetic electron flux enhancements in the drift loss cone

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