Phase‐bunching effects in triggered VLF emissions: Antenna effect

Trakhtengerts, V. Yu.; Демехов, А. Г.; Hobara, Y.; Hayakawa, Masashi

doi:10.1029/2002ja009415

Cited by 15 publications

(20 citation statements)

References 18 publications

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“…Thus, the accelerated field‐aligned beam should be very unstable relative to the generation of whistler waves. This regime of generation is similar to triggered whistler wave emission [e.g., Nunn , ; Trakhtengerts et al , ]. Therefore, we suggest that particle trapping can produce high‐amplitude KAW‐shape electron beams with substantial source of free energy, while secondary instability of such beams can result in efficient generation of whistler waves in the region of plasma injection.…”

Section: Discussionsupporting

confidence: 72%

Electron trapping and acceleration by kinetic Alfven waves in the inner magnetosphere

2015

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In this paper we study the interaction of kinetic Alfven waves generated near the equatorial plane of the magnetosphere with electrons having initial energies up to ∼100 eV. Wave‐particle interactions are investigated using a theoretical model of trapping into an effective potential generated by the wave parallel electric field and the mirror force acting along geomagnetic field lines. It is demonstrated that waves with an effective potential amplitude on the order of ∼100–400 V and with perpendicular wavelengths on the order of the ion gyroradius can trap and efficiently accelerate electrons up to energies of several keV. Trapping acceleration corresponds to conservation of the electron magnetic moment and, thus, results in a significant decrease of the electron equatorial pitch angle with time. Analytical and numerical estimates of the maximum energy and probability of trapping are presented, and the application of the proposed model is discussed.

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Section: Discussionsupporting

confidence: 72%

Electron trapping and acceleration by kinetic Alfven waves in the inner magnetosphere

2015

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“…Under such conditions, phase bunching and trapping can occur (e.g. Albert, 2002;Trakhtengerts et al, 2003). Future theoretical work on non-linear scattering is required.…”

Section: Article In Pressmentioning

confidence: 96%

Review of radiation belt relativistic electron losses

Millan

Thorne

2007

Journal of Atmospheric and Solar-Terrestrial Physics

455

454

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“…In summary, in the region ζ < 0 the spectrum of chorus elements is mainly formed due to the so-called antenna effect whose role for triggered VLF emissions was considered in papers [27,28].…”

Section: Transition To Falling Tones In the Magnetospheric Bwo By Incmentioning

confidence: 99%

Generation of VLF emissions with the increasing and decreasing frequency in the magnetosperic cyclotron maser in the backward wave oscillator regime

Демехов

2011

Radiophys Quantum El

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We study the mechanisms of the formation of falling tones in the dynamic spectrum of whistlermode waves generated by energetic electrons in the Earth's magnetosphere when the backwardwave oscillator (BWO) regime is realized in the magnetospheric cyclotron maser. As was shown earlier, this regime allows one to explain many features of ELF/VLF chorus emissions in the magnetosphere, in particular, the generation of elements with discrete frequency spectrum, characterized by a large growth rate and a fast frequency drift. On the basis of numerical simulations of a simplified system of nonlinear equations describing the magnetospheric BWO dynamics under the assumption of small efficiency of wave-particle interactions we show that the falling tones are generated in the case where the generation region is shifted from the equatorial plane (geomagnetic-field minimum) upstream with respect to the motion of energetic electrons. In this case, the resonant electrons move towards the decreasing magnetic field in the process of generation; hence, their longitudinal velocity increases, which corresponds to a decrease in the cyclotron-resonance frequency. Two mechanisms of the shift of the generation region from the equator are considered, i.e., (i) an increase in the linear instability growth rate (e. g., due to an increase in the energetic-electron density), and (ii) persistence of the phase bunching of the particles coming back to the generation region due to the bounce oscillations. We show that both of these mechanisms can result in the formation of falling tones, but the properties of the generated emissions such as the frequency drift rate and characteristic time interval between the elements are different. The conditions of preserving the phase bunching due to the bounce oscillations are discussed. Probably, this mechanism can operate in the case where the length of the generation region along the magnetic field is close to the characteristic bounce-oscillation length of energetic electrons which is realized for a sufficiently high cold-plasma density in the generation region.

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Phase‐bunching effects in triggered VLF emissions: Antenna effect

Cited by 15 publications

References 18 publications

Electron trapping and acceleration by kinetic Alfven waves in the inner magnetosphere

Electron trapping and acceleration by kinetic Alfven waves in the inner magnetosphere

Review of radiation belt relativistic electron losses

Generation of VLF emissions with the increasing and decreasing frequency in the magnetosperic cyclotron maser in the backward wave oscillator regime

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