Abstract

Abstract. Pitch-angle diffusion coefficients have been calculated for resonant interaction with electrostatic electron cyclotron harmonic (ECH) waves in the magnetospheres of Earth, Jupiter, Saturn, Uranus and Neptune. Calculations have been performed at two radial distances of each planet. It is found that observed wave electric field amplitudes in the magnetospheres of Earth and Jupiter are sufficient to put electrons on strong diffusion in the energy range of less than 100 eV. However, for Saturn, Uranus and Neptune, the observed ECH wave amplitude are insufficient to put electrons on strong diffusion at any radial distance.

Highlights

  • Electrostatic electron cyclotron harmonic (ECH) waves are virtually ubiquitous in planetary magnetospheres

  • We extend the calculations of pitch-angle diffusion coefficients for resonant interaction with ECH waves in the magnetospheres of Earth, Jupiter, Saturn, Uranus and Neptune

  • The ECH waves of natural origin were first observed by the OGO-5 satellite (Kennel et al, 1970; Fredricks and Scarf, 1973) as narrow band ( f/fc ≈ 1.0), large amplitude (1–10 mV m−1) waves that appear within a frequency range of 1.25fc < f < 1.75fc

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Summary

Introduction

Horne and Thorne (2000) have calculated the bounceaveraged pitch-angle diffusion rates for electrostatic ECH waves driven by a loss-cone distribution They have concluded that ECH waves can scatter keV electrons into the loss-cone efficiently and can contribute directly to the loss to the atmosphere. We extend the calculations of pitch-angle diffusion coefficients for resonant interaction with ECH waves in the magnetospheres of Earth, Jupiter, Saturn, Uranus and Neptune. This will provide a comparative study of pitch-angle diffusion in producing diffuse aurora in planetary atmospheres for the first time. The comparison of pitch-angle diffusion with strong diffusion and precipitation of energetic electrons into the atmosphere of each planet and results and discussion of this study, are presented in Sect.

Observations of ECH waves
Jupiter
Saturn
Uranus
Neptune
Plasma parameters
Calculation de1tEai-l3s
Conclusions
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