Evaluation of a space-observed electric field structure for the ability to destabilize inhomogeneous energy-density-driven waves

I V Golovchanskaya,I V Mingalev,M N Melnik,B V Kozelov,A A Lubchich

doi:10.5194/angeo-32-1-2014

I V Golovchanskaya, I V Mingalev + Show 3 more

Open Access

https://doi.org/10.5194/angeo-32-1-2014

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Journal: Annales Geophysicae	Publication Date: Jan 10, 2014
Citations: 30	License type: CC BY 3.0

Affiliation: Polar Geophysical Institute

Abstract

Abstract. We examine the effectiveness of nonuniform, quasistatic, transverse electric fields that are often observed in the auroral region in destabilization of inhomogeneous energy-density-driven (IEDD) waves. Specifically, the IEDD dispersion relation of Ganguli et al. (1985a, b) is evaluated for an electric field structure observed by the FAST satellite in the auroral ionosphere at 1000 km altitude. The background field-aligned current, plasma density and ion composition are derived from FAST observations. Other input parameters adopted in the calculations are varied in pertinent ranges. Unstable solutions are obtained that indicate a variety of frequencies and perpendicular wavelengths. These can manifest as a broadband spectrum of IEDD waves.

Highlights

It has been demonstrated in numerous studies that the broadband extremely low frequency (BBELF) waves that are often detected in the auroral ionosphere, as reported by Bonnell et al (1996), Ergun et al (1998), Kintner et al (2000) and others, can hardly be explained in terms of the current-driven electrostatic ion-cyclotron instability (CDEICI) (Drummond and Rosenbluth, 1962; Kindel and Kennel, 1971)
We evaluate the inhomogeneous energydensity-driven (IEDD) dispersion relation of Ganguli et al (1985a, b) for the E field configuration shown in Fig. 2, bottom right panel, and for assumptions made plausible from space observations described in the previous section
In the previous sections we demonstrated that the nonuniform electric fields that are observed in the auroral region can destabilize the broadband electrostatic waves via the mechanism of IEDD instability proposed by Ganguli et al (1985a, b) and generalized by Ganguli and Palmadesso (1988), Gavrishchaka et al (1996), Reynolds and Ganguli (1998) and others

Summary

Introduction

It has been demonstrated in numerous studies that the broadband extremely low frequency (BBELF) waves that are often detected in the auroral ionosphere, as reported by Bonnell et al (1996), Ergun et al (1998), Kintner et al (2000) and others, can hardly be explained in terms of the current-driven electrostatic ion-cyclotron instability (CDEICI) (Drummond and Rosenbluth, 1962; Kindel and Kennel, 1971). In the theoretical studies of Ganguli and Palmadesso (1988), Ganguli et al (1994), and Gavrishchaka et al (1996), it was shown that by changing the resonance properties of the system a combination of transverse localized electric fields and fieldaligned currents results in a lower excitation threshold current for CDEIC waves than inferred from the classical theory of the CDEIC instability. This theoretical prediction was validated in a number of laboratory experiments (Koepke and Amatucci, 1992; Amatucci et al, 1994; Koepke et al, 1994).

Setting the equilibrium configuration

Evaluation of the IEDD dispersion relation

Discussion