Pitch angle distributions of solar energetic particles and the local scattering properties of the interplanetary medium

1986 ◽  
Vol 311 ◽  
pp. 437 ◽  
Author(s):  
J. Beeck ◽  
G. Wibberenz
Keyword(s):  
Pitch Angle ◽  
Interplanetary Medium ◽  
Energetic Particles ◽  
Solar Energetic Particles

scholarly journals On the Turbulent Reduction of Drifts for Solar Energetic Particles

2021 ◽  
Vol 922 (2) ◽  
pp. 200
Author(s):  
J. P. van den Berg ◽  
N. E. Engelbrecht ◽  
N. Wijsen ◽  
R. D. Strauss
Keyword(s):  
Pitch Angle ◽  
Cosmic Ray ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Particle Distributions ◽  
Magnetic Turbulence ◽  
Field Diffusion ◽  
Background Magnetic Field ◽  
Perpendicular Diffusion ◽  
Inner Heliosphere

Abstract Particle drifts perpendicular to the background magnetic field have been proposed by some authors as an explanation for the very efficient perpendicular transport of solar energetic particles (SEPs). This process, however, competes with perpendicular diffusion caused by magnetic turbulence, which can also disrupt the drift patterns and reduce the magnitude of drift effects. The latter phenomenon is well known in cosmic-ray studies, but not yet considered in SEP models. Additionally, SEP models that do not include drifts, especially for electrons, use turbulent drift reduction as a justification of this omission, without critically evaluating or testing this assumption. This article presents the first theoretical step for a theory of drift suppression in SEP transport. This is done by deriving the turbulence-dependent drift reduction function with a pitch-angle dependence, as is applicable for anisotropic particle distributions, and by investigating to what extent drifts will be reduced in the inner heliosphere for realistic turbulence conditions and different pitch-angle dependencies of the perpendicular diffusion coefficient. The influence of the derived turbulent drift reduction factors on the transport of SEPs are tested, using a state-of-the-art SEP transport code, for several expressions of theoretically derived perpendicular diffusion coefficients. It is found, for realistic turbulence conditions in the inner heliosphere, that cross-field diffusion will have the largest influence on the perpendicular transport of SEPs, as opposed to particle drifts.

Interplanetary pitch angle scattering and coronal transport of solar energetic particles: New information from Helios

1980 ◽  
Vol 85 (A5) ◽  
pp. 2313 ◽  
Author(s):  
J.W. Bieber ◽  
J.A. Earl ◽  
G. Green ◽  
H. Kunow ◽  
R. Müller-Mellin ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
New Information ◽  
Angle Scattering

scholarly journals Cross-field transport and pitch-angle anisotropy of solar energetic particles in MHD turbulence

2016 ◽  
Vol 2 ◽  
pp. 63-65 ◽  
Author(s):  
F. Fraschetti
Keyword(s):  
Pitch Angle ◽  
Turbulence Models ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Mhd Turbulence ◽  
First Order ◽  
Angle Dependence ◽  
Inhomogeneous Turbulence ◽  
Angle Scattering

Abstract. Recent modelling of solar energetic particles (SEPs) propagation through the heliospheric turbulence, also discussed in this workshop, has investigated the role of the pitch-angle scattering and the perpendicular transport in spreading particles in heliolongitude, as shown by multi-spacecraft measurements (STEREO A/B, ACE, SOHO, etc.) at 1 AU in various energy ranges. In some events the first-order pitch-angle anisotropy of the particles distribution is not-negligible. We calculate the average perpendicular displacement due to the gradient/curvature drift in an inhomogeneous turbulence accounting for pitch-angle dependence for two MHD turbulence models: (a) 3-D isotropic, (b) anisotropic as conjectured by Goldreich-Sridhar. We find in both cases that the drift scales as (1 − μ2)2 with the cosine of pitch-angle μ, in contrast with previous models for transport of SEPs. This result can impact the models of propagation of SEPs through the heliosphere.

Propagation of solar particles in the interplanetary medium

1980 ◽  
Vol 297 (1433) ◽  
pp. 629-640 ◽  
Keyword(s):  
Time Dependence ◽  
Experimental Evidence ◽  
Particle Transport ◽  
Pitch Angle ◽  
Interplanetary Medium ◽  
Transport Coefficients ◽  
Energetic Particles ◽  
Transport Equations ◽  
Interplanetary Shocks ◽  
The Earth

Our view of the spectrum and time dependence of the energetic particles accelerated during flare events is distorted by the diffusion and energy changes that take place during the propagation of the particles through the interplanetary medium. We describe theoretical attempts to calculate the transport coefficients in space and energy and to represent the observed time dependence and pitch angle distributions both near the Earth and on distant space probes. Particular attention is given to the interplanetary acceleration processes that are thought to occur, both in the neighbourhood of interplanetary shocks and generally throughout the interplanetary medium. Current experimental evidence on these effects are reviewed. Revised particle transport equations which take into account the acceleration are discussed.

Assessing the Predictability of Solar Energetic Particles with the Use of Machine Learning Techniques

Solar Physics ◽  
2021 ◽  
Vol 296 (7) ◽  
Author(s):  
E. Lavasa ◽  
G. Giannopoulos ◽  
A. Papaioannou ◽  
A. Anastasiadis ◽  
I. A. Daglis ◽  
...  
Keyword(s):  
Machine Learning ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
Machine Learning Techniques ◽  
Learning Techniques
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