Energy Release And Particle Acceleration At The Sun And In The Heliosphere

Energetic particles are accelerated in rich profusion at sites throughout the heliosphere. They come from solar flares in the low corona, from shock waves driven outward by coronal mass ejections (CMEs), from planetary magnetospheres and bow shocks. They come from corotating interaction regions (CIRs) produced by high-speed streams in the solar wind, and from the heliospheric termination shock at the outer edge of the heliospheric cavity. We sample all these populations near Earth, but can distinguish them readily by their element and isotope abundances, ionization states, energy spectra, angular distributions and time behavior. Remote spacecraft have probed the spatial distributions of the particles and examined new sources in situ. Most acceleration sources can be "seen" only by direct observation of the particles; few photons are produced at these sites. Wave-particle interactions are an essential feature in acceleration sources and, for shock acceleration, new evidence of energetic-proton-generated waves has come from abundance variations and from local cross-field scattering. Element abundances often tell us the physics the source plasma itself, prior to acceleration. By comparing different populations, we learn more about the sources, and about the physics of acceleration and transport, than we can possibly learn from one source alone.

All papers have been peer-reviewed. Our star is a very effective particle accelerator. Energies up to GeVs have been observed in Solar energetic particle events. These events are often associated with solar flares and/or Coronal Mass Ejections. Understanding how particles are accelerated in these phenomena has been an outstanding problem in space plasma physics for a long time. Part of the reason is its practical (e.g. Space weather) and fundamental (cosmic ray origin) importance. In this conference we review recent progresses on this problem, with a balance between observations, theories and numerical simulations. Specific topics include 1) particle acceleration at flare site, 2) turbulence properties of the solar wind, 3) particle acceleration and transport in the inner heliosphere, 4) particle acceleration at the termination shock and heliosheath, and 5) particle acceleration at supernova remnant shocks.

Observations and physical concepts are interwoven to give basic explanations of phenomena and also show the limitations in these explanations and identify some fundamental questions. Compared to conventional plasma physics textbooks this book focuses on the concepts relevant in the large-scale space plasmas. It combines basic concepts with current research and new observations in interplanetary space and in the magnetospheres. Graduate students and young researchers starting to work in this special field of science, will find the numerous references to review articles as well as important original papers helpful to orientate themselves in the literature. Emphasis is on energetic particles and their interaction with the plasma as examples for non-thermal phenomena, shocks and their role in particle acceleration as examples for non-linear phenomena. This second edition has been updated and extended. Improvements include: the use of SI units; addition of recent results from SOHO and Ulysses; improved treatment of the magnetosphere as a dynamic phenomenon; text restructured to provide a closer coupling between basic physical concepts and observed complex phenomena.

This concise primer introduces the non-specialist reader to the physics of solar energetic particles (SEP) and systematically reviews the evidence for the two main mechanisms which lead to the so-called impulsive and gradual SEP events. More specifically, the timing of the onsets, the longitude distributions, the high-energy spectral shapes, the correlations with other solar phenomena (e.g. coronal mass ejections), as well as the all-important elemental and isotopic abundances of SEPs are investigated. Impulsive SEP events are related to magnetic reconnection in solar flares and jets. The concept of shock acceleration by scattering on self-amplified Alfvén waves is introduced, as is the evidence of reacceleration of impulsive-SEP material in the seed population accessed by the shocks in gradual events. The text then develops processes of transport of ions out to an observer. Finally, a new technique to determine the source plasma temperature in both impulsive and gradual events is demonstrated. Last but not least the role of SEP events as a radiation hazard in space is mentioned and a short discussion of the nature of the main particle telescope designs that have contributed to most of the SEP measurements is given.

This volume helps the reader to understand the ways and means of how dynamical phenomena are generated at the Sun, how they travel through the Heliosphere, and how they affect Earth. It provides an integrated account of the three principal chains of events all the way from the Sun to Earth: the normal solar wind, coronal mass ejections, and solar energetic particles.

The transport of solar energetic particles (SEPs) in the inner heliosphere is a very important issue which can affect our daily life. For example, large SEP events can lead to the failure of power grids, interrupt communications, and may participate in global climate change. The SEPS also can harm humans in space and destroy the instruments on board spacecraft. Studying the transport of SEPs also helps us understand remote regions of space which are not visible to us because there are not enough photons in those places. The interplanetary magnetic field is the medium in which solar energetic particles travel. The Parker Model of the solar wind and its successor, the Weber and Davis model, have been the dominant models of the solar wind and the interplanetary magnetic field since 1960s. In this thesis, I have reviewed these models and applied an important correction to the Weber and Davis model. Various solar wind models and their limitations are presented. Different models can affect the calculation of magnetic field direction at 1ÃU by as much as about 30\%. Analysis of the onset of SEP events could be used to infer the release time of solar energetic particles and to differentiate between models of particle acceleration near the Sun. It is demonstrated that because of the nature of the stochastic heliospheric magnetic field, the path length measured along the lineof force can be shorter than that of the nominal Parker spiral. These results help to explain recent observations. A two dimensional model and a fully three dimensional numerical model for the transport of SEPs has been developed based on Parker's transport equation for the first time. R̀̀eservoir'' phenomenon, which means the inner heliosphere works like a reservoir for SEPs during large SEP events, and multi-spacecraft observation of peak intensities are explained by this numerical model.

The review articles collected in this volume present a critical assessment of particle acceleration mechanisms and observations from suprathermal particles in the magnetosphere and heliosphere to high-energy cosmic rays, thus covering a range of energies over seventeen orders of magnitude, from 103 eV to 1020 eV. The main themes are observations of accelerated populations from the magnetosphere to extragalactic scales and assessments of the physical processes underlying particle acceleration in different environments (magnetospheres, the solar atmosphere, the heliosphere, supernova remnants, pulsar wind nebulae and relativistic outflows). Several contributions review the status of shock acceleration in different environments and also the role of turbulence in particle acceleration. Observational results are compared with modelling in different parameter regimes. The book concludes with contributions on the status of particle acceleration research and its future perspectives. This volume is aimed at graduate students and researchers active in astrophysics and space science. Previously published in Space Science Reviews journal, Vol. 173 Nos. 1-4, 2012.