Observations of kinetic scale field line resonances

Christopher C. Chaston; John W. Bonnell; John R Wygant; Forrest Mozer; Stuart D. Bale; Kris Kersten; Aaron W Breneman; Craig A. Kletzing; William S. Kurth; George B. Hospodarsky; Charles W. Smith; Elizabeth A. Macdonald

doi:10.1002/2013GL058507

Observations of kinetic scale field line resonances

Christopher C. Chaston, John W. Bonnell, John R Wygant, Forrest Mozer, Stuart D. Bale, Kris Kersten, Aaron W Breneman, Craig A. Kletzing, William S. Kurth, George B. Hospodarsky, Charles W. Smith, Elizabeth A. Macdonald

Physics and Astronomy (Twin Cities)

Research output: Contribution to journal › Article › peer-review

74 Scopus citations

Abstract

We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfvénic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρ_i) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (k_τ) extending to k _τρ_i ≫ 1. The amplitude of these waves is such that E/B_o ≳ Ω_i/k_τ (E, B _o, and Ω_i are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential.

Original language	English (US)
Pages (from-to)	209-215
Number of pages	7
Journal	Geophysical Research Letters
Volume	41
Issue number	2
DOIs	https://doi.org/10.1002/2013GL058507
State	Published - Jan 28 2014

Keywords

alfven waves
field lines resonances
injections
kinetic effects
particle accleration

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10.1002/2013GL058507

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@article{ec60c69ed42043f69a341d4c447bf9e6,

title = "Observations of kinetic scale field line resonances",

abstract = "We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfv{\'e}nic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (kτ) extending to k τρi ≫ 1. The amplitude of these waves is such that E/Bo ≳ Ωi/kτ (E, B o, and Ωi are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential.",

keywords = "alfven waves, field lines resonances, injections, kinetic effects, particle accleration",

author = "Chaston, {Christopher C.} and Bonnell, {John W.} and Wygant, {John R} and Forrest Mozer and Bale, {Stuart D.} and Kris Kersten and Breneman, {Aaron W} and Kletzing, {Craig A.} and Kurth, {William S.} and Hospodarsky, {George B.} and Smith, {Charles W.} and Macdonald, {Elizabeth A.}",

year = "2014",

month = jan,

day = "28",

doi = "10.1002/2013GL058507",

language = "English (US)",

volume = "41",

pages = "209--215",

journal = "Geophysical Research Letters",

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publisher = "John Wiley and Sons Inc.",

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TY - JOUR

T1 - Observations of kinetic scale field line resonances

AU - Chaston, Christopher C.

AU - Bonnell, John W.

AU - Wygant, John R

AU - Mozer, Forrest

AU - Bale, Stuart D.

AU - Kersten, Kris

AU - Breneman, Aaron W

AU - Kletzing, Craig A.

AU - Kurth, William S.

AU - Hospodarsky, George B.

AU - Smith, Charles W.

AU - Macdonald, Elizabeth A.

PY - 2014/1/28

Y1 - 2014/1/28

N2 - We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfvénic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (kτ) extending to k τρi ≫ 1. The amplitude of these waves is such that E/Bo ≳ Ωi/kτ (E, B o, and Ωi are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential.

AB - We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfvénic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (kτ) extending to k τρi ≫ 1. The amplitude of these waves is such that E/Bo ≳ Ωi/kτ (E, B o, and Ωi are the wave amplitude, background field strength, and ion gyro-frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential.

KW - alfven waves

KW - field lines resonances

KW - injections

KW - kinetic effects

KW - particle accleration

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JO - Geophysical Research Letters

JF - Geophysical Research Letters

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Observations of kinetic scale field line resonances

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