Effects of ion abundances on electromagnetic ion cyclotron wave growth rate in the vicinity of the plasmapause

Henning, F. D.; Mace, R. L.

doi:10.1063/1.4873375

Cited by 11 publications

(14 citation statements)

References 39 publications

(56 reference statements)

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“…First, nonlinear processes might play a part in the evolution of the vanishing stop band since the waves in our case have a large amplitude of 5 nT (see Figure 1c). Next, as demonstrated in Mace et al [2011] and Henning and Mace [2014], hot H + ions with a kappa distribution could play an important role in the generation of the instabilities of all three EMIC branches. It seems that hot H + ions with kappa distributions might take some effects in the vanishing stop band.…”

Section: Discussionmentioning

confidence: 88%

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In situ evidence of the modification of the parallel propagation of EMIC waves by heated He⁺ ions

Yuan

Wang

et al. 2016

JGR Space Physics

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With observations of the Van Allen Probe B, we report in situ evidence of the modification of the parallel propagating electromagnetic ion cyclotron (EMIC) waves by heated He+ ions. In the outer boundary of the plasmasphere, accompanied with the He+ ion heating, the frequency bands of H+ and He+ for EMIC waves merged into each other, leading to the disappearance of a usual stop band between the gyrofrequency of He+ ions (ΩHe+) and the H+ cutoff frequency (ωH+co) in the cold plasma. Moreover, the dispersion relation for EMIC waves theoretically calculated with the observed plasma parameters also demonstrates that EMIC waves can indeed parallel propagate across ΩHe+. Therefore, the paper provides an in situ evidence of the modification of the parallel propagation of EMIC waves by heated He+ ions.

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Section: Discussionmentioning

confidence: 88%

“…Next, as demonstrated in Mace et al . [] and Henning and Mace [], hot H + ions with a kappa distribution could play an important role in the generation of the instabilities of all three EMIC branches. It seems that hot H + ions with kappa distributions might take some effects in the vanishing stop band.…”

Section: Discussionmentioning

confidence: 99%

In situ evidence of the modification of the parallel propagation of EMIC waves by heated He⁺ ions

Yuan

Wang

et al. 2016

JGR Space Physics

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“…However, O + abundances can be highly variable and minor ion abundances play a role in the dispersion relation and the calculation of the diffusion coefficients. Some previous studies have used linear kinetic theory [e.g., Mace et al ., ; Henning and Mace , ; Wang et al ., ] or hybrid simulations [e.g., Denton and Hu , ; Denton et al ., ] to show that high He + abundance or high O + ion abundance strongly suppresses the growth of H + band EMIC waves. Since this study focuses on the role of H + band EMIC waves in driving the bounce resonance with radiation belt electrons, we have therefore adopted the above set of ion concentration ratios for our numerical calculations.…”

Section: Discussionmentioning

confidence: 99%

Bounce resonance scattering of radiation belt electrons by H⁺ band EMIC waves

Cao

Summers

et al. 2017

JGR Space Physics

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We perform a detailed analysis of bounce‐resonant pitch angle scattering of radiation belt electrons due to electromagnetic ion cyclotron (EMIC) waves. It is found that EMIC waves can resonate with near‐equatorially mirroring electrons over a wide range of L shells and energies. H+ band EMIC waves efficiently scatter radiation belt electrons of energy >100 keV from near 90° pitch angles to lower pitch angles where the cyclotron resonance mechanism can take over to further diffuse electrons into the loss cone. Bounce‐resonant electron pitch angle scattering rates show a strong dependence on L shell, wave normal angle distribution, and wave spectral properties. We find distinct quantitative differences between EMIC wave‐induced bounce‐resonant and cyclotron‐resonant diffusion coefficients. Cyclotron‐resonant electron scattering by EMIC waves has been well studied and found to be a potentially crucial electron scattering mechanism. The new investigation here demonstrates that bounce‐resonant electron scattering may also be very important. We conclude that bounce resonance scattering by EMIC waves should be incorporated into future modeling efforts of radiation belt electron dynamics.

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“…To include these effects in the analysis, we assume the electrons bi-Kappa distributed (Summers & Thorne 1991), a model widely invoked to describe the kinetic instabilities in space plasmas (Mace et al 2011;Kourakis et al 2012;Lazar 2012;Henning and Mace 2014;Lazar et al 2015). In Section 2 we introduce the distribution models for electrons and protons, and provide the dispersion relation for the EMIC modes.…”

Section: Introductionmentioning

confidence: 99%

Effects of suprathermal electrons on the proton temperature anisotropy in space plasmas: Electromagnetic ion-cyclotron instability

Shaaban

Lazar

Poedts³

et al. 2016

Astrophys Space Sci

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In collision-poor plasmas from space, e.g., the solar wind and planetary magnetospheres, the kinetic anisotropy of the plasma particles is expected to be regulated by the kinetic instabilities. Driven by an excess of ion (proton) temperature perpendicular to the magnetic field (T ⊥ > T ), the electromagnetic ion-cyclotron (EMIC) instability is fast enough to constrain the proton anisotropy, but the observations do not conform to the instability thresholds predicted by the standard theory for bi-Maxwellian models of the plasma particles. This paper presents an extended investigation of the EMIC instability in the presence of suprathermal electrons which are ubiquitous in these environments. The analysis is based on the kinetic (Vlasov-Maxwell) theory assuming that both species, protons and electrons, may be anisotropic, and the EMIC unstable solutions are derived numerically providing an accurate description for conditions typically encountered in space plasmas. The effects of suprathermal populations are triggered by the electron anisotropy and the temperature contrast between electrons and protons. For certain conditions the anisotropy thresholds exceed the limits of the proton anisotropy measured in the solar wind considerably restraining the unstable regimes of the EMIC modes.

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Effects of ion abundances on electromagnetic ion cyclotron wave growth rate in the vicinity of the plasmapause

Cited by 11 publications

References 39 publications

In situ evidence of the modification of the parallel propagation of EMIC waves by heated He⁺ ions

In situ evidence of the modification of the parallel propagation of EMIC waves by heated He⁺ ions

Bounce resonance scattering of radiation belt electrons by H⁺ band EMIC waves

Effects of suprathermal electrons on the proton temperature anisotropy in space plasmas: Electromagnetic ion-cyclotron instability

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Effects of ion abundances on electromagnetic ion cyclotron wave growth rate in the vicinity of the plasmapause

Cited by 11 publications

References 39 publications

In situ evidence of the modification of the parallel propagation of EMIC waves by heated He+ ions

In situ evidence of the modification of the parallel propagation of EMIC waves by heated He+ ions

Bounce resonance scattering of radiation belt electrons by H+ band EMIC waves

Effects of suprathermal electrons on the proton temperature anisotropy in space plasmas: Electromagnetic ion-cyclotron instability

Contact Info

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About

In situ evidence of the modification of the parallel propagation of EMIC waves by heated He⁺ ions

In situ evidence of the modification of the parallel propagation of EMIC waves by heated He⁺ ions

Bounce resonance scattering of radiation belt electrons by H⁺ band EMIC waves