Electron holes in the outer radiation belt: Characteristics and their role in electron energization

Vasko, I. Y.; Agapitov, Oleksiy; Mozer, F. S.; Artemyev, А. V.; Drake, J. F.; Kuzichev, Ilya

doi:10.1002/2016ja023083

Cited by 35 publications

(57 citation statements)

References 90 publications

(159 reference statements)

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“…The properties of phase space holes observed by the Burst 1 data are now compared with phase space hole properties derived from Burst 2 observations, specifically with Vasko, Agapitov, Mozer, Artemyev, Drake, and Kuzichev (), where the amplitude, phase velocity, magnetic spike signature, parallel width, and potential depth of 100 electron phase space holes were examined using Burst 2 data. Vasko, Agapitov, Mozer, Artemyev, Krasnoselskikh, and Bonnell () used the Vasko, Agapitov, Mozer, Artemyev, Drake, and Kuzichev () results to define typical electron hole properties from which they derived diffusion coefficients describing the diffusive scattering of electrons by electron phase space holes. The diffusion coefficients computed by Vasko, Agapitov, Mozer, Artemyev, Krasnoselskikh, and Bonnell () were based on electron hole parameters as determined using amplitude‐biased Burst 2 data.…”

Section: Observationsmentioning

confidence: 99%

“…This identification consists simply of integrating the E ∥ electric field waveform in time to estimate the shape of the electric potential associated with each solitary wave Φ( t ) =

\int E_{∥} (t) v_{ϕ} normald t

. A symmetric phase space hole will have a near‐Gaussian potential profile indicative of no net potential drop (see Vasko, Agapitov, Mozer, Artemyev, Drake, & Kuzichev, , and references therein). The hole velocity v ϕ is assumed constant during the brief period of observation, so it has no effect on the shape of Φ( t ).…”

Section: Observationsmentioning

confidence: 99%

“…Following (Vasko, Agapitov, Mozer, Artemyev, Drake, & Kuzichev, ), the potential depth and parallel spatial scale of a phase space hole are estimated using a Gaussian best fit to the measured potential profile Φ( t ) of the form describing an idealized phase space hole potential profile:

Φ_{ideal} = Φ_{0} e^{- v_{ϕ}^{2} t^{2} / 2 d_{∥}^{2}}

. Again, the Gaussian fit must satisfy the good fit criteria described earlier.…”

Section: Observationsmentioning

confidence: 99%

“…Figure summarizes the observed phase space hole properties. To facilitate comparison between the Burst 1 (unbiased) and Burst 2 (triggered) data, this figure shows the same quantities, in the same format, with the same horizontal axes as Figure 3 from Vasko, Agapitov, Mozer, Artemyev, Drake, and Kuzichev () (except Figure 6c, where the axis is defined by Vasko, Agapitov, Mozer, Artemyev, Drake, & Kuzichev, , does not apply). The vertical axes of all panels in Figure (except Figure c) show the fraction of all 1,084 identified phase space holes with velocity estimates in each histogram bin.…”

Section: Observationsmentioning

confidence: 99%

“…Using the Van Allen Probes high‐resolution electric and magnetic field time series data (burst data), researchers have demonstrated that this broadband power is due to waves and structures such as electron‐acoustic solitons (Agapitov et al, ; Mozer et al, ; Vasko, Agapitov, Mozer, Bonnell, et al, ), ion‐acoustic double layers (Malaspina et al, ), electron phase space holes (Malaspina et al, ; Vasko, Agapitov, Mozer, Artemyev et al, ; Vasko, Agapitov, Mozer, Artemyev, Krasnoselskikh, & Bonnell, ), nonlinear whistler mode waves (Gao et al, ; Mozer et al, ), and kinetic Alfvén waves (Chaston et al, , ; Malaspina, Claudepierre, et al, ).…”

Section: Introductionmentioning

confidence: 99%

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A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere

et al. 2018

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Now that observations have conclusively established that the inner magnetosphere is abundantly populated with kinetic electric field structures and nonlinear waves, attention has turned to quantifying the ability of these structures and waves to scatter and accelerate inner magnetospheric plasma populations. A necessary step in that quantification is determining the distribution of observed structure and wave properties (e.g., occurrence rates, amplitudes, and spatial scales). Kinetic structures and nonlinear waves have broadband signatures in frequency space, and consequently, high‐resolution time domain electric and magnetic field data are required to uniquely identify such structures and waves as well as determine their properties. However, most high‐resolution fields data are collected with a strong bias toward high‐amplitude signals in a preselected frequency range, strongly biasing observations of structure and wave properties. In this study, an ∼45 min unbroken interval of 16,384 samples/s field burst data, encompassing an electron injection event, is examined. This data set enables an unbiased census of the kinetic structures and nonlinear waves driven by this electron injection, as well as determination of their “typical” properties. It is found that the properties determined using this unbiased burst data are considerably different than those inferred from amplitude‐biased burst data, with significant implications for wave‐particle interactions due to kinetic structures and nonlinear waves in the inner magnetosphere.

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Section: Observationsmentioning

confidence: 99%

“…This identification consists simply of integrating the E ∥ electric field waveform in time to estimate the shape of the electric potential associated with each solitary wave Φ( t ) =

\int E_{∥} (t) v_{ϕ} normald t

Section: Observationsmentioning

confidence: 99%

Φ_{ideal} = Φ_{0} e^{- v_{ϕ}^{2} t^{2} / 2 d_{∥}^{2}}

. Again, the Gaussian fit must satisfy the good fit criteria described earlier.…”

Section: Observationsmentioning

confidence: 99%

Section: Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere

et al. 2018

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Diffusive scattering of electrons by electron holes around injection fronts

Vasko

Agapitov

Mozer³

et al. 2017

JGR Space Physics

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Van Allen Probes have detected nonlinear electrostatic spikes around injection fronts in the outer radiation belt. These spikes include electron holes (EH), double layers, and more complicated solitary waves. We show that EHs can efficiently scatter electrons due to their substantial transverse electric fields. Although the electron scattering driven by EHs is diffusive, it cannot be evaluated via the standard quasi‐linear theory. We derive analytical formulas describing local electron scattering by a single EH and verify them via test particle simulations. We show that the most efficiently scattered are gyroresonant electrons (crossing EH on a time scale comparable to the local electron gyroperiod). We compute bounce‐averaged diffusion coefficients and demonstrate their dependence on the EH spatial distribution (latitudinal extent and spatial filling factor) and individual EH parameters (amplitude of electrostatic potential, velocity, and spatial scales). We show that EHs can drive pitch angle scattering of ≲5 keV electrons at rates 10−2−10−4 s−1 and, hence, can contribute to electron losses and conjugated diffuse aurora brightenings. The momentum and pitch angle scattering rates can be comparable, so that EHs can also provide efficient electron heating. The scattering rates driven by EHs at L shells L ∼ 5–8 are comparable to those due to chorus waves and may exceed those due to electron cyclotron harmonics.

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Pulsating auroras produced by interactions of electrons and time domain structures

et al. 2017

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Previous evidence has suggested that either lower band chorus waves or kinetic Alfven waves scatter equatorial kilovolt electrons that propagate to lower altitudes where they precipitate or undergo further low‐altitude scattering to make pulsating auroras. Recently, time domain structures (TDSs) were shown, both theoretically and experimentally, to efficiently scatter equatorial electrons. To assess the relative importance of these three mechanisms for production of pulsating auroras, 11 intervals of equatorial THEMIS data and a 4 h interval of Van Allen Probe measurements have been analyzed. During these events, lower band chorus waves produced only negligible modifications of the equatorial electron distributions. During the several TDS events, the equatorial 0.1–3 keV electrons became magnetic field‐aligned. Kinetic Alfven waves may also have had a small electron scattering effect. The conclusion of these studies is that time domain structures caused the most important equatorial scattering of ~1 keV electrons toward the loss cone to provide the main electron contribution to pulsating auroras. Chorus wave scattering may have provided part of the highest energy (>10 keV) electrons in such auroras.

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Electron holes in the outer radiation belt: Characteristics and their role in electron energization

Cited by 35 publications

References 90 publications

A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere

A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere

Diffusive scattering of electrons by electron holes around injection fronts

Pulsating auroras produced by interactions of electrons and time domain structures

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