Search Publications
The Heliospheric Magnetic Field
Balogh, André; Erdõs, Géza
The Heliospheric Magnetic Field (HMF) is the physical framework in which energetic particles and cosmic rays propagate. Changes in the large scale structure of the magnetic field lead to short- and long term changes in cosmic ray intensities, in particular in anti-phase with solar activity. The origin of the HMF in the corona is well understood an…
Mechanisms of Spontaneous Reconnection: From Magnetospheric to Fusion Plasma
Zelenyi, Lev; Artemyev, Anton
Very often space plasma is treated as collisionless. We check the validity of this paradigm considering various regimes of tearing mode (spontaneous reconnection) including effects of particle collisions and shear of magnetic field. We briefly describe Pitaevskii's effect of effective modification of collision frequency due to the finite particle …
Microphysics in Astrophysical Plasmas
Schwartz, Steven J.; Zweibel, Ellen G.; Goldman, Martin
Although macroscale features dominate astrophysical images and energetics, the physics is controlled through microscale transport processes (conduction, diffusion) that mediate the flow of mass, momentum, energy, and charge. These microphysical processes manifest themselves in key (all) boundary layers and also operate within the body of the plasm…
Properties of Ground Level Enhancement Events and the Associated Solar Eruptions During Solar Cycle 23
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +3 more
Solar cycle 23 witnessed the most complete set of observations of coronal mass ejections (CMEs) associated with the Ground Level Enhancement (GLE) events. We present an overview of the observed properties of the GLEs and those of the two associated phenomena, viz., flares and CMEs, both being potential sources of particle acceleration. Although we…
Particle Acceleration in the Magnetotail and Aurora
Zelenyi, L. M.; Baker, D. N.; Artemyev, A. V. +3 more
This paper deals with acceleration processes in the magnetotail and the processes that enhance particle precipitation from the tail into the ionosphere through electric fields in the auroral acceleration region, generating or intensifying discrete auroral arcs. Particle acceleration in the magnetotail is closely related to substorms and the occurr…
Magnetic Reconnection in the Solar Wind
Gosling, J. T.
It is only within the last 5 years that we have learned how to recognize the unambiguous signature of magnetic reconnection in the solar wind in the form of roughly Alfvénic accelerated plasma flows embedded within bifurcated magnetic field reversal regions (current sheets). This paper provides a brief overview of what has since been learned about…
Anisotropy in Space Plasma Turbulence: Solar Wind Observations
Horbury, T. S.; Chen, C. H. K.; Wicks, R. T.
The local magnetic field induces many types of anisotropy in plasma turbulence, changing the rate of energy transfer and affecting the propagation of energetic particles. It is challenging to measure this anisotropy in the solar wind due to the limited number of sampling points and measurement difficulties and many aspects remain poorly understood…
Ion Acceleration at the Earth's Bow Shock
Möbius, E.; Scholer, M.; Burgess, D.
The Earth's bow shock is the most studied example of a collisionless shock in the solar system. It is also widely used to model or predict the behaviour at other astrophysical shock systems. Spacecraft observations, theoretical modelling and numerical simulations have led to a detailed understanding of the bow shock structure, the spatial organiza…
What Are Special About Ground-Level Events?. Flares, CMEs, Active Regions and Magnetic Field Connection
Liu, Y.; Nitta, N. V.; Nightingale, R. W. +1 more
Ground level events (GLEs) occupy the high-energy end of gradual solar energetic particle (SEP) events. They are associated with coronal mass ejections (CMEs) and solar flares, but we still do not clearly understand the special conditions that produce these rare events. During Solar Cycle 23, a total of 16 GLEs were registered, by ground-based neu…
Solar Wind Models from the Chromosphere to 1 AU
Velli, Marco; Hansteen, Viggo H.
Recent models of the fast solar wind are characterized by low coronal electron temperatures while proton, α-particle, and minor ion temperatures are expected to be quite high and generally anisotropic, including large temperatures perpendicular to the magnetic field and parallel beams. This entails that the electric field should be relatively unim…