Parallel velocity mixing yielding enhanced electron heating during magnetic pumping

Egedal, J.; Schroeder, J.; Lichko, Emily

doi:10.1017/s0022377821000088

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…As shown by Egedal et al. (2021), multiple local maxima in are associated with separate locally trapped populations and in a dynamically changing configuration orbit transitions can lead to energization through mixing. This effect of energization by mixing of separate trapped populations is not addressed here.…”

Section: Pressure Anisotropy In the Limits Of Fast Transit Time And No Pitch Angle Scatteringmentioning

confidence: 87%

“…This derivation will then in separate papers be generalized and combined with related heating mechanisms (Egedal et al. 2021) to account for magnetic pumping in more general magnetic perturbations including compressional waves of multiple amplitudes and phases.…”

Section: Simple Picture Of Magnetic Pumping With Trapped Electronsmentioning

confidence: 99%

“…It should be emphasized that the present analysis applies a prescribed and highly idealized magnetic perturbation. As such, further work is required to generalize the results to more general configurations including parallel velocity mixing (Egedal, Schroeder & Lichko 2021) and to characterized the feedback/damping of the energization process on the magnetic perturbations.…”

Section: Introductionmentioning

confidence: 99%

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The fast transit-time limit of magnetic pumping with trapped electrons

Egedal

Lichko

2021

J. Plasma Phys.

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Recently, the energization of superthermal electrons at the Earth's bow shock was found to be consistent with a new magnetic pumping model derived in the limit where the electron transit time is much shorter than any time scale governing the evolution of the magnetic fields. The new model breaks with the common approach of integrating the kinetic equations along unperturbed orbits. Rather, the fast transit-time limit allows the electron dynamics to be characterized by adiabatic invariants (action variables) accurately capturing the nonlinear effects of electrons becoming trapped in magnetic perturbations. Without trapping, fast parallel streaming along magnetic field lines causes the electron pressure to be isotropized and homogeneous along the magnetic field lines. In contrast, trapping permits spatially varying pressure anisotropy to form along the magnetic field lines, and through a Fermi process this pressure anisotropy in turn becomes the main ingredient that renders magnetic pumping efficient for energizing superthermal electrons. We here present a detailed mathematical derivation of the model.

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Section: Pressure Anisotropy In the Limits Of Fast Transit Time And No Pitch Angle Scatteringmentioning

confidence: 87%

Section: Simple Picture Of Magnetic Pumping With Trapped Electronsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The fast transit-time limit of magnetic pumping with trapped electrons

Egedal

Lichko

2021

J. Plasma Phys.

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Recent Developments in Particle Acceleration at Shocks: Theory and Observations

et al. 2022

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Energetic particles represent an important component of the plasma in the heliosphere. They range from particles accelerated at impulsive events in the solar corona and at large scale structures in the interplanetary medium, to anomalous cosmic rays accelerated at the boundaries of the heliosphere. In-situ satellite observations, numerical simulations and theoretical models have advanced, often in a cooperative way, our knowledge on the acceleration processes involved. In this paper we review recent developments on particle acceleration, with major emphasis on shock acceleration, giving an overview of recent observations at interplanetary shocks and at the termination shock of the solar wind. We discuss their interpretation in terms of analytical models and numerical simulations. The influence of the particle transport properties on the acceleration mechanism will also be addressed.

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Pitch angle scattering of fast particles by low frequency magnetic fluctuations

Egedal

2022

Physics of Plasmas

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The adiabatic invariance of the magnetic moment during particle motion is of fundamental importance to the dynamics of magnetized plasma. The related rate of pitch angle scattering is investigated here for fast particles that thermally stream through static magnetic perturbations. For a uniform magnetic field with a localized perturbation, it is found that the curvature parameter κ2=min(Rc/ρL) does not predict the level of pitch angle scattering. Instead, based on numerical integration of particle orbits in prescribed magnetic fields, we derive predictions for the particle scattering rates, which can be characterized by the relative perturbation amplitude A≃δB/B, and the particle Larmor radius normalized by the field-aligned wavelength of the perturbations, ρL/λ||. Particles with ρL/λ||≃1 are subject to strong pitch angle scattering, while the level of scattering vanishes for both the limits of ρL/λ||≪1 and ρL/λ||≫1. The results are summarized in terms of a scattering operator, suitable for including the described scattering in basic kinetic models.

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Parallel velocity mixing yielding enhanced electron heating during magnetic pumping

Cited by 5 publications

References 24 publications

The fast transit-time limit of magnetic pumping with trapped electrons

The fast transit-time limit of magnetic pumping with trapped electrons

Recent Developments in Particle Acceleration at Shocks: Theory and Observations

Pitch angle scattering of fast particles by low frequency magnetic fluctuations

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