Energy flux in 2‐D MHD waveguide in the outer magnetosphere

Mazur, V. A.; Chuiko, D. A.

doi:10.1002/2016ja023632

Cited by 7 publications

(6 citation statements)

References 43 publications

(51 reference statements)

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“…They are customarily divided into two types: azimuthally large-and small-scale waves (e.g., Dai et al, 2015;Leonovich & Klimushkin, 2015). The large-scale examples are Alfvén waves with the low azimuthal wave numbers (m ∼ 1) generated mostly by mechanisms associated with the solar wind (Agapitov et al, 2009;Agapitov & Cheremnykh, 2013;Hartinger et al, 2015;Mazur & Chuiko, 2017;Potapov, 2013). On the other hand, the small-scale Pc4-5 waves (high azimuthal wave numbers, m ≫ 1) are usually thought to be driven by unstable particle populations inside the magnetosphere (Dai et al, 2013;Ozeke & Mann, 2001;Yeoman et al, 2016), although external processes can also play an important role (Hao et al, 2017;Zong et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Drift Resonance of Compressional ULF Waves and Substorm‐Injected Protons From Multipoint THEMIS Measurements

et al. 2018

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A compressional Pc5 wave associated with localized hot proton injection was observed by the five THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft in the dusk sector of the Earth's magnetosphere at L ∼ 10R E on 21 May 2007. The wave magnetic field perturbation transverse to the background magnetic field was primarily poloidal, in agreement with the predominately azimuthal wave vector direction (with westward phase velocity). The observation followed two consecutive substorms, when the cloud of energetic particles comprised of the lower-energy protons from the earlier substorm was mixed with higher-energy protons from the subsequent one. The clear signatures of the wave-particle drift resonance of protons modulated by the wave were observed. The wave period was found to be about 2 times longer than the corresponding Alfvén wave eigenmode period on the same L-shells calculated with the THEMIS data. The increase of the particle energy with the distance from the Earth and the observed strong dependence of the wave frequency on the azimuthal wave number constitutes conditions for the gradient instability of the drift compressional mode (for the Alfvén mode one supposes the particle energy decrease with radial distance). Based on these results, we conclude that the observed wave was the drift compressional mode generated by the gradient instability.

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Section: Introductionmentioning

confidence: 99%

Drift Resonance of Compressional ULF Waves and Substorm‐Injected Protons From Multipoint THEMIS Measurements

et al. 2018

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“…Such a interplanetary shock induced vortices flow has been indeed observed by (Huttunen et al, ; Tian et al, ) in the magnetotail plasma sheet. The generated vortices will further generate ULF waves at certain frequencies depending on the azimuthal phase velocity of the vortices (Mazur & Chuiko, ; Wright & Rickard, ). As the fast‐mode wave propagates toward the magnetosphere, it can be amplified by the Kelvin‐Helmholtz instability (Mazur & Chuiko, ), and the field line resonance can be excited (Fedorov et al, ; Leonovich et al, ).…”

Section: Discussionmentioning

confidence: 99%

Alfvén Wave Generation by a Compact Source Moving on the Magnetopause: Asymptotic Solution

et al. 2019

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The spatiotemporal structure of Alfvén waves excited by a moving pressure pulse on the magnetopause is analytically explored. These waves are supposed to be responsible for field-aligned currents generating traveling convection vortices in the ionosphere. It is found that a moving source generates two wave modes, a primary and a secondary mode, having different azimuthal wave vectors and frequencies. Both modes represent surface waves with amplitudes exponentially decreasing from the magnetopause. At a given azimuthal location, they also decrease with time as the source passes away. For the primary mode, the wave frequency equals the Alfvén resonant frequency on the surface of the source, while for the secondary mode the frequency equals the local resonant frequency. The dependence of the frequency of the secondary mode on the radial coordinate results in phase mixing, which leads to a change of the wave polarization from mixed into toroidal polarization. For both primary and secondary modes, the azimuthal component of the wave vector equals the corresponding wave frequency divided by the speed of the source. Superposition of the primary and secondary modes produces plasma vortices behind the source. Plain Language SummaryThe spatiotemporal structure of Alfvén waves excited by a moving pressure pulse on the magnetopause is analytically explored. It is found that a moving source generates two wave modes, a primary and a secondary mode, having different azimuthal wave vectors and frequencies.Both modes represent surface waves with amplitudes exponentially decreasing from the magnetopause. At a given azimuthal location, they also decrease with time as the source passes away. For the primary mode, the wave frequency equals the Alfvén resonant frequency on the surface of the source, while for the secondary mode the frequency equals the local resonant frequency. For both primary and secondary modes, the azimuthal component of the wave vector equals the corresponding wave frequency divided by the speed of the source. Superposition of the primary and secondary modes produces plasma vortices behind the source.In general plasma physics, the generation of Alfvén waves by a moving source (a specific kind of the Cerenkov radiation problem) was first considered by Dokuchaev (1968). The idea of a moving source was

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“…Как показывают радарные наблюдения, волнам с большими m свойственно распространение в направлении экватора [Tian et al, 1991;Yeoman et al, 1992. Для случая взаимодействия волн с протонами Mager et al [2009] предложили объяснение, связывающее смещение фазового фронта волны с зависимостью скорости движения заряженных частиц в азимутальном направлении от расстояния до Земли. Поскольку на дальних магнитных оболочках скорость дрейфа выше, облако заряженных частиц растягивается в экваториальной плоскости в виде спирали, что приводит к движению волны в сторону Земли, или, в случае проекций силовых линий на поверхность, к распространению от полюса к экватору.…”

Section: Discussionunclassified

“…Что касается волн с малыми азимутальными волновыми числами, то, поскольку их источники находятся в солнечном ветре либо связаны с его взаимодействием с магнитосферой, они преимущественно распространяются в направлении от подсолнечной точки [Мазур, Чуйко, 2011;Mazur, Chuiko, 2013].…”

Section: Introductionunclassified

Observing magnetospheric waves propagating in the direction of electron drift with Ekaterinburg Decameter Coherent Radar

Челпанов¹,

Mager²,

Климушкин³

et al. 2019

Solnechno-Zemnaya Fizika

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This paper deals with Pc5 magnetospheric pulsations featuring positive azimuthal wave numbers registered with the mid-latitude coherent decameter radar located near Ekaterinburg (EKB). The azimuthal wave numbers are determined using adjacent high time resolution beams directed toward the magnetic pole. Approximately 13 % of all steady waves registered with the radar propagate eastward. We have examined ten cases of wave observations with both small and high positive wave numbers, which occurred between April 2014 and March 2015. We performed a wavelet analysis of the data sets, estimated wavelength in radial direction for four cases, and determined meridional phase propagation direction. In three cases, the results are consistent with field line resonance behavior. However, in the majority of the studied events wave frequencies are considerably lower than those of field line resonance, which were derived from satellite data on magnetic field and particle density. These waves may be classed with the drift-compressional mode.

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Energy flux in 2‐D MHD waveguide in the outer magnetosphere

Cited by 7 publications

References 43 publications

Drift Resonance of Compressional ULF Waves and Substorm‐Injected Protons From Multipoint THEMIS Measurements

Drift Resonance of Compressional ULF Waves and Substorm‐Injected Protons From Multipoint THEMIS Measurements

Alfvén Wave Generation by a Compact Source Moving on the Magnetopause: Asymptotic Solution

Observing magnetospheric waves propagating in the direction of electron drift with Ekaterinburg Decameter Coherent Radar

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