Nonresonant Interaction of Charged Energetic Particles With Low-Frequency Noncompressive Turbulence: Numerical Simulation

Ragot, B. R.

doi:10.1088/0004-637x/758/2/89

Cited by 8 publications

(3 citation statements)

References 51 publications

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“…This implies that the dropout events likely originate from small localized regions on the Sun. Other interpretations of the impulsive-SEP-dropout phenomena invoke: (1) temporary trapping of particles within small-scale structures followed by rapid magnetic-field line diffusion (e.g., Ruffolo et al 2003;Chuychai et al 2007); (2) interplanetary turbulence that allows the magnetic-field lines to meander and spread out independently of supergranulation (Ragot 2012;Laitinen et al 2013b); (3) stochastic nature of the time-varying magnetic connectivity to the source regions in the presence of magnetic turbulence (Ruffolo and Matthaeus 2015). Chollet et al (2009) used the Giacalone et al (2000a) interpretation, along with in-situ observations of electrons and ions, to infer the source locations (longitude and latitude in the solar atmosphere) of impulsive SEP events.…”

Section: Flux Dropoutsmentioning

confidence: 99%

Large gradual solar energetic particle events

Desai

Giacalone

2016

Living Rev. Sol. Phys.

420

305

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Solar energetic particles, or SEPs, from suprathermal (few keV) up to relativistic (∼few GeV) energies are accelerated near the Sun in at least two ways: (1) by magnetic reconnection-driven processes during solar flares resulting in impulsive SEPs, and (2) at fast coronal-mass-ejection-driven shock waves that produce large gradual SEP events. Large gradual SEP events are of particular interest because the accompanying high-energy (>10s MeV) protons pose serious radiation threats to human explorers living and working beyond low-Earth orbit and to technological assets such as communications and scientific satellites in space. However, a complete understanding of these large SEP events has eluded us primarily because their properties, as observed in Earth orbit, are smeared due to mixing and contributions from many important physical effects. This paper provides a comprehensive review of the current state of knowledge of these important phenomena, and summarizes some of the key questions that will be addressed by two upcoming missions-NASA's Solar Probe Plus and ESA's Solar Orbiter. Both of these missions are designed to directly and repeatedly sample the near-Sun environments where interplanetary scattering and transport effects are significantly reduced, allowing us to discriminate between different acceleration sites and mechanisms and to isolate the contributions of numerous physical processes occurring during large SEP events.

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Section: Flux Dropoutsmentioning

confidence: 99%

Large gradual solar energetic particle events

Desai

Giacalone

2016

Living Rev. Sol. Phys.

420

305

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“…As indicated by the green lines showing the mean ρ-spread (minus ρ 0 ) of MFLs initially separated from L 0 by ρ 0 = 10 7 , 10 8 , 10 9 , 10 10 , and 10 11 cm, it would remain small for any injection distance shorter than 10 11 cm (still by a factor of 3 or 4 for 10 11 cm because more distant MFLs separate more slowly; R09). Three-dimensional views of this and higherenergy electron trajectories and local MFLs can be seen in Ragot (2012).…”

Section: Introductionmentioning

confidence: 99%

Solar Wind Magnetic Field Line Dispersal: Multispacecraft Analysis and Comparison with Theoretical Results

Ragot

2023

ApJ

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The dominance of the global over the relative, cross-field transport of magnetic field lines (MFLs), up to scales of a couple of hours in the solar wind (SW), has been predicted both theoretically and numerically, in the approximation of self-similar, single-level power spectra of magnetic fluctuations. Here the predictions for the MFL relative cross-field transport or dispersal are tested against the results of in situ data analysis, using 23 yr of field and flow measurements on board ACE and Wind. The theoretical results are confirmed/refined by nonlinear theoretical computations and corrected to include the effects of power-level variability or intermittency. Other than confirming earlier theoretical findings at the separation scales ρ between a few ×1010 cm and the large-separation limit, with a ballistic regime followed by decorrelation and transition to diffusion in the ( ln ρ , θ ) -space, the new study reveals two new supradiffusive regimes in ln ρ and clock angle θ for the MFL dispersal, distinct from a drift-induced supradiffusion found earlier, and distinct from each other. The first supradiffusion, of the nonlinear computations, is a simple nonlinear effect, which cannot be recovered by data analysis at two spacecraft of fixed separation on the analysis timescale. The second supradiffusion, of the data analysis, is much stronger for ρ < few × 1010 cm than the two previous supradiffusions, and it becomes stronger at shorter separations. It follows the ballistic regime without transition through diffusion and is recovered by multiscale, theoretical estimates. It is a Lévy-type supradiffusion, due to the intermittency observed in the SW.

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“…In the early works [ Dessler and Karplus , ; McIlwain , ], outward adiabatic transport was proposed to explain the electron flux dropout during geomagnetic storms (with the buildup of magnetospheric ring current) [ Kim and Chan , ; Su et al , ]. Recently, some nonadiabatic loss processes have been identified, such as magnetopause shadowing [ Li et al , ; Desorgher et al , ] and various wave‐particle resonant [ Horne and Thorne , ; Summers et al , ; Green et al , ; Thorne , ; Elkington et al , ; Shprits et al , ; Loto'Aniu et al , ; Su et al , ; Breneman et al , ; Zhu et al , ; Gao et al , ] and nonresonant [ Qin and Shalchi , ; Ragot , ; Lemons , ; Camporeale , ; Chen et al , ] interactions. These nonadiabatic mechanisms can act not only in storm times [e.g, Bortnik et al , ; Su et al , ; Turner et al , , ; Hudson et al , ] but also in nonstorm times [ Su et al , ].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear fundamental and harmonic cyclotron resonant scattering of radiation belt ultrarelativistic electrons by oblique monochromatic EMIC waves

Wang

Zheng

et al. 2017

JGR Space Physics

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Cyclotron resonant scattering by electromagnetic ion cyclotron (EMIC) waves has been considered to be responsible for the rapid loss of radiation belt high‐energy electrons. For parallel‐propagating EMIC waves, the nonlinear character of cyclotron resonance has been revealed in recent studies. Here we present the first study on the nonlinear fundamental and harmonic cyclotron resonant scattering of radiation belt ultrarelativistic electrons by oblique EMIC waves on the basis of test particle simulations. Higher wave obliquity produces stronger nonlinearity of harmonic resonances but weaker nonlinearity of fundamental resonance. Compared to the quasi‐linear prediction, these nonlinear resonances yield a more rapid loss of electrons over a wider pitch angle range. In the quasi‐linear regime, the ultrarelativistic electrons are lost in the equatorial pitch angle range αeq<75°, nearly independent of wave normal angle ψ. In contrast, the upper pitch angle cutoff of nonlinear losses tends to increase with the wave normal angle increasing, which is about αeq=82° at ψ = 0° and αeq>87.5° at ψ = 20° and 40°. At the resonant pitch angles αeq<75°, the difference between quasi‐linear and nonlinear loss timescales tends to decrease with the wave normal angle increasing. At ψ = 0° and 20°, the nonlinear electron loss timescale is 10% shorter than the quasi‐linear prediction; at ψ = 40°, the difference in loss timescales is reduced to <5%.

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Nonresonant Interaction of Charged Energetic Particles With Low-Frequency Noncompressive Turbulence: Numerical Simulation

Cited by 8 publications

References 51 publications

Large gradual solar energetic particle events

Large gradual solar energetic particle events

Solar Wind Magnetic Field Line Dispersal: Multispacecraft Analysis and Comparison with Theoretical Results

Nonlinear fundamental and harmonic cyclotron resonant scattering of radiation belt ultrarelativistic electrons by oblique monochromatic EMIC waves

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