Pitch angle scattering of relativistic electrons near electromagnetic ion cyclotron resonances in diverging magnetic fields

Eliasson, Bengt; Papadopoulos, K.

doi:10.1088/1361-6587/aa8100

Cited by 4 publications

(4 citation statements)

References 34 publications

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“…1B) shows enhancements around the frequencies of heavy ion gyro-periods, indicating that these waves are electromagnetic ion cyclotron (EMIC) waves associated with these ion species. The phase speed of EMIC waves is generally smaller than the Alfvén velocity (19). EMIC waves are often generated in the central plasma sheet.…”

Section: Resultsmentioning

confidence: 99%

Revealing the source of Jupiter’s x-ray auroral flares

et al. 2021

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Jupiter’s rapidly rotating, strong magnetic field provides a natural laboratory that is key to understanding the dynamics of high-energy plasmas. Spectacular auroral x-ray flares are diagnostic of the most energetic processes governing magnetospheres but seemingly unique to Jupiter. Since their discovery 40 years ago, the processes that produce Jupiter’s x-ray flares have remained unknown. Here, we report simultaneous in situ satellite and space-based telescope observations that reveal the processes that produce Jupiter’s x-ray flares, showing surprising similarities to terrestrial ion aurora. Planetary-scale electromagnetic waves are observed to modulate electromagnetic ion cyclotron waves, periodically causing heavy ions to precipitate and produce Jupiter’s x-ray pulses. Our findings show that ion aurorae share common mechanisms across planetary systems, despite temporal, spatial, and energetic scales varying by orders of magnitude.

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Section: Resultsmentioning

confidence: 99%

Revealing the source of Jupiter’s x-ray auroral flares

et al. 2021

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“…In view of applications (see e.g. [20,35]), the whistler dispersion relation τ w has more impact near the resonance, that is when |ξ| becomes large enough.…”

Section: The Origin Of the Modelmentioning

confidence: 99%

“…Examples include the Alfvén wave regime as opposed to the Whistler wave regime, see e.g. [20,35]. By this way, the PDE (3.2) is reduced to a coupled system of N scalar equations…”

Section: General Setting and Assumptionsmentioning

confidence: 99%

Constructive and destructive interferences in nonlinear hyperbolic equations

Carles

Cheverry

2022

msmf

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This article introduces a physically realistic model for explaining how electromagnetic waves can be internally generated, propagate and interact in strongly magnetized plasmas or in nuclear magnetic resonance experiments. It studies high frequency solutions of nonlinear hyperbolic equations for time scales at which dispersive and nonlinear effects can be present in the leading term of the solutions. It explains how the produced waves can accumulate during long times to produce constructive and destructive interferences which, in the above contexts, are part of turbulent effects.

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“…In that setting, shear Alfvén waves propagating in bands near or above the species' gyrofrequencies are called electromagnetic ion cyclotron (EMIC) waves (Young et al 1981;Roux et al 1982;Fraser & Nguyen 2001). EMIC waves play an important role in the Earth's radiation belts, where they can be excited by Doppler-shifted cyclotron resonance (DCR) with energetic ions and subsequently can interact with trapped relativistic electrons, causing scattering and precipitation (Cornwall, Coroniti & Thorne 1970;Summers & Thorne 2003;Eliasson & Papadopoulos 2017). In magnetically confined plasmas for fusion energy research, such as tokamaks, Alfvén eigenmodes (AEs) can be excited by energetic particles that could be created by heating schemes (such as neutral beam injection or heating by radiofrequency (RF) waves) or by fusion reactions (e.g.…”

Section: Introductionmentioning

confidence: 99%

Propagation of shear Alfvén waves in a two-ion plasma and application as a diagnostic for the ion density ratio

2020

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In this paper, we propose an efficient diagnostic technique for determining spatially resolved measurements of the ion density ratio in a magnetized two-ion species plasma. Shear Alfvén waves were injected into a mixed helium–neon plasma using a magnetic loop antenna, for frequencies spanning the ion cyclotron regime. Two distinct propagation bands are observed, bounded by $\omega < \varOmega _\textrm {Ne}$ and $\omega _{ii} < \omega < \varOmega _\textrm {He}$ , where $\omega _{ii}$ is the ion–ion hybrid cutoff frequency and $\varOmega _\textrm {He}$ and $\varOmega _\textrm {Ne}$ are the helium and neon cyclotron frequencies, respectively. A theoretical analysis of the cutoff frequency was performed and shows it to be largely unaffected by kinetic electron effects and collisionality, although it can deviate significantly from $\omega _{{ii}}$ in the presence of warm ions due to ion finite Larmor radius effects. A new diagnostic technique and accompanying algorithm was developed in which the measured parallel wavenumber $k_\parallel$ is numerically fit to the predicted inertial Alfvén wave dispersion in order to resolve the local ion density ratio. A major advantage of this algorithm is that it only requires a measurement of $k_\parallel$ and the background magnetic field in order to be employed. This diagnostic was tested on the Large Plasma Device at UCLA and was successful in yielding radially localized measurements of the ion density ratio.

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Pitch angle scattering of relativistic electrons near electromagnetic ion cyclotron resonances in diverging magnetic fields

Cited by 4 publications

References 34 publications

Revealing the source of Jupiter’s x-ray auroral flares

Revealing the source of Jupiter’s x-ray auroral flares

Constructive and destructive interferences in nonlinear hyperbolic equations

Propagation of shear Alfvén waves in a two-ion plasma and application as a diagnostic for the ion density ratio

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