Nonlinear subcyclotron resonance as a formationmechanism for gaps in banded chorus

Fu, Xiangrong; Guo, Zehua; Dong, Chuanfei; Gary, S. Peter

doi:10.1002/2015gl064182

Cited by 18 publications

(19 citation statements)

References 24 publications

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“…For the linear Landau damping mechanism, ray tracing studies show that waves at 0.5f ce suffer significant damping only after they have propagated a significant distance from the equatorial region (see, e.g., Bortnik et al, 2006). Similar argument could be made about the subcyclotron resonance mechanism proposed by Fu et al (2015). The nonlinear damping mechanism by Omura et al (2009) cannot be applied to explain this study, because the damping rate of this mechanism and its dependence on plasma parameters are not given.…”

Section: Discussionmentioning

confidence: 68%

“…Tsurutani and Smith (1974) suggested that Landau damping by electrons with energy of cyclotron resonance but traveling at the same direction as the wave might be responsible for the power gap. Fu et al (2015) suggested that the subcyclotron resonance between large amplitude whistler waves and energetic electrons may be responsible of the multiple power gaps of chorus reported by Macúšová et al (2014). Fu et al (2015) suggested that the subcyclotron resonance between large amplitude whistler waves and energetic electrons may be responsible of the multiple power gaps of chorus reported by Macúšová et al (2014).…”

Section: Introductionmentioning

confidence: 97%

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Typical Characteristics of Whistler Mode Waves Categorized by Their Spectral Properties Using Van Allen Probes Observations

Teng

Tao

2019

Geophysical Research Letters

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Properties of banded, no‐gap, lower band only, and upper band only whistler mode waves (0.1–0.8fce) outside the plasmasphere are investigated using Van Allen Probes data. Our analysis shows that no‐gap whistler waves have higher occurrence rate at morning side and dayside, while banded and lower band only waves have higher occurrence rate between midnight and dawn. We also find that the occurrence rate of no‐gap whistler waves peaks at magnetic latitude |MLAT|∼8–10°, while banded waves have higher occurrence rate near the equator for false|MLATfalse|≲6°. The wave normal angle distributions of these four groups of waves are similar to previous results. The distinct local time and latitudinal distribution of no‐gap and banded whistler mode waves is critical to further understand the formation mechanism of the power minimum at half electron gyrofrequency.

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Section: Discussionmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 97%

Typical Characteristics of Whistler Mode Waves Categorized by Their Spectral Properties Using Van Allen Probes Observations

Teng

Tao

2019

Geophysical Research Letters

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“…The evidences of this nonlinear damping mechanism have been observed by Geotail satellite in Yagitani et al (). Fu et al () performed subcyclotron resonance, which might lead to the formation of the gap by test particle simulations in a homogeneous background magnetic field. However, the gradient of the background magnetic field is essential for nonlinear wave‐particle interactions (Omura et al, ).…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Damping of Oblique Whistler Mode Waves Via Landau Resonance

Hsieh

Omura

2018

JGR Space Physics

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Nonlinear trapping of electrons via Landau resonance is an important mechanism of oblique whistler mode wave‐particle interactions. Electrons trapped by Landau resonance gain energies from waves. The Landau resonance velocity becomes very close to the group velocity of nearly parallel whistler mode waves at frequencies around half the electron gyrofrequency, resulting in a long interaction time and possible wave damping. We perform test particle simulations with parameters at L = 5 and a small wave normal angle 10° to study the wave‐particle interactions via the Landau resonance. Analyzing the wave electric fields and the resonant currents formed by electrons undergoing Landau and cyclotron resonances, we show that effective wave damping occurs near half the electron gyrofrequency. This nonlinear wave damping is contributed by Landau resonance rather than cyclotron resonance. Furthermore, we confirm that this damping is dominated by perpendicular components of the wave electric field and perpendicular resonant currents. The simulation results indicate that nonlinear damping via Landau resonance is one of the mechanisms dividing chorus emissions into the upper band and the lower band.

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“…The lower band ( ∕Ω e < 0.5, is the wave frequency) is dominantly parallel propagating with some portion close to the resonance cone [Agapitov et al, 2013;Li et al, 2013], whereas the upper band ( ∕Ω e > 0.5) has a broad range of wave normal angles between 0 ∘ and 60 ∘ [Li et al, 2013]. Several mechanisms have been proposed to account for the banded structure of chorus [Omura et al, 2009;Liu et al, 2011;Fu et al, 2014;Mourenas et al, 2015;Fu et al, 2015]. Among the proposed mechanisms, Mourenas et al [2015] suggested that the less frequently occurring but statistically significant very oblique lower band chorus waves can be generated through a combination of cyclotron resonance and Landau resonance with low-energy electron beams having an energy of a few keV.…”

Section: Introductionmentioning

confidence: 99%

Resonant excitation of whistler waves by a helical electron beam

Compernolle

Bortnik

et al. 2016

Geophysical Research Letters

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Chorus‐like whistler mode waves that are known to play a fundamental role in driving radiation belt dynamics are excited on the Large Plasma Device by the injection of a helical electron beam into a cold plasma. The mode structure of the excited whistler wave is identified using a phase correlation technique showing that the waves are excited through a combination of Landau resonance, cyclotron resonance, and anomalous cyclotron resonance. The dominant wave mode excited through cyclotron resonance is quasi‐parallel propagating, whereas wave modes excited through Landau resonance and anomalous cyclotron resonance propagate at oblique angles that are close to the resonance cone. An analysis of the linear wave growth rates captures the major observations in the experiment. The results have important implications for the generation process of whistler waves in the Earth's inner magnetosphere.

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Nonlinear subcyclotron resonance as a formationmechanism for gaps in banded chorus

Cited by 18 publications

References 24 publications

Typical Characteristics of Whistler Mode Waves Categorized by Their Spectral Properties Using Van Allen Probes Observations

Typical Characteristics of Whistler Mode Waves Categorized by Their Spectral Properties Using Van Allen Probes Observations

Nonlinear Damping of Oblique Whistler Mode Waves Via Landau Resonance

Resonant excitation of whistler waves by a helical electron beam

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