The role of magnetic helicity for field line diffusion and drift

Tautz, R. C.; Lerche, I.

doi:10.1051/0004-6361/201117063

Cited by 5 publications

(2 citation statements)

References 37 publications

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“…Ruffolo et al (2008), for instance, studied perpendicular diffusion of energetic particles in two-component asymmetric turbulence. Furthermore, we often neglect magnetic helicity but this effect and its importance in particle transport theory was also explored in some previous work (see, e.g., Dung and Schlickeiser 1990;Tautz and Lerche 2011). As shown in Matthaeus and Smith (1981), the components of the spectral tensor have the following form P nm (k) = g(k , k ⊥ ) δ nm − k n k m k 2…”

Section: Model Dynamical Correlation Functionmentioning

confidence: 99%

Perpendicular Transport of Energetic Particles in Magnetic Turbulence

Shalchi

2020

Space Sci Rev

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Scientists have explored how energetic particles such as solar energetic particles and cosmic rays move through a magnetized plasma such as the interplanetary and interstellar medium since more than five decades. From a theoretical point of view, this topic is difficult because the particles experience complicated interactions with turbulent magnetic fields. Besides turbulent fields, there are also large scale or mean magnetic fields breaking the symmetry in such systems and one has to distinguish between transport of particles parallel and perpendicular with respect to such mean fields. In standard descriptions of transport phenomena, one often assumes that the transport in both directions is normal diffusive but non-diffusive transport was found in more recent work. This is in particular true for early and intermediate times where the diffusive regime is not yet reached. In recent years researchers employed advanced numerical tools in order to simulate the motion of those particles through the aforementioned systems. Nevertheless, the analytical description of the problem discussed here is of utmost importance since analytical forms of particle transport parameters need to be known in several applications such as solar modulation studies or investigations of shock acceleration. The latter process is directly linked to the question of what the sources of high energy cosmic rays are, a problem which is considered to be one of the most important problems of the sciences of the 21st century. The present review article discusses analytical theories developed for describing particle transport across a large scale magnetic field as well as field line random walk. A heuristic approach explaining the basic physics of perpendicular transport is also presented. Simple analytical forms for the perpendicular diffusion coefficient are proposed which can easily be incorporated in numerical codes for solar modulation or shock acceleration studies. Test-particle simulations are also discussed together with a comparison with analytical results. Several applications such as cosmic ray propagation and diffusive shock acceleration are also part of this review.

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Section: Model Dynamical Correlation Functionmentioning

confidence: 99%

Perpendicular Transport of Energetic Particles in Magnetic Turbulence

Shalchi

2020

Space Sci Rev

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“…with κ and κ ⊥ describing diffusion along and across the magnetic field, respectively, and κ A covering drift effects due to magnetic field curvature (Tautz & Lerche 2011;Tautz & Shalchi 2012). In order to solve the transport equation, the diffusion coefficients have to be known in advance.…”

Section: Test-particle Transportmentioning

confidence: 99%

Cosmic wave‐particle interactions: Astrophysical magnetic turbulence and high‐energy particles

Tautz¹

2014

Astron Nachr

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Understanding the origin and the properties of energetic charged particles has been an important problems of both plasma astro‐physics and astroparticle physics. Here, an introduction is given about the complicated interaction processes between cosmic rays and turbulent electromagnetic fields. First, the formation of turbulent electromagnetic fields due to plasma instabilities is discussed. Second, the microphysics of particle scattering due to such turbulent fields is explained and a comparison with measurements in the Solar wind is shown. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Theory of Cosmic Ray Transport in the Heliosphere

et al. 2022

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Modelling the transport of cosmic rays (CRs) in the heliosphere represents a global challenge in the field of heliophysics, in that such a study, if it were to be performed from first principles, requires the careful modelling of both large scale heliospheric plasma quantities (such as the global structure of the heliosphere, or the heliospheric magnetic field) and small scale plasma quantities (such as various turbulence-related quantities). Here, recent advances in our understanding of the transport of galactic cosmic rays are reviewed, with an emphasis on new developments pertaining to their transport coefficients, with a special emphasis on novel theoretical and numerical simulation results, as well as the CR transport studies that employ them. Furthermore, brief reviews are given of recent progress in CR focused transport modelling, as well as the modelling of non-diffusive CR transport.

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The role of magnetic helicity for field line diffusion and drift

Cited by 5 publications

References 37 publications

Perpendicular Transport of Energetic Particles in Magnetic Turbulence

Perpendicular Transport of Energetic Particles in Magnetic Turbulence

Cosmic wave‐particle interactions: Astrophysical magnetic turbulence and high‐energy particles

Theory of Cosmic Ray Transport in the Heliosphere

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