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Shock Acceleration of Ions in the Heliosphere

Lee, Martin A. and Mewaldt, R. A. and Giacalone, J. (2012) Shock Acceleration of Ions in the Heliosphere. Space Science Reviews, 173 (1-4). pp. 247-281. ISSN 0038-6308.

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Energetic particles constitute an important component of the heliospheric plasma environment. They range from solar energetic particles in the inner heliosphere to the anomalous cosmic rays accelerated at the interface of the heliosphere with the local interstellar medium. Although stochastic acceleration by fluctuating electric fields and processes associated with magnetic reconnection may account for some of the particle populations, the majority are accelerated by the variety of shock waves present in the solar wind. This review focuses on “gradual” solar energetic particle (SEP) events including their energetic storm particle (ESP) phase, which is observed if and when an associated shock wave passes Earth. Gradual SEP events are the intense long-duration events responsible for most space weather disturbances of Earth’s magnetosphere and upper atmosphere. The major characteristics of gradual SEP events are first described including their association with shocks and coronal mass ejections (CMEs), their ion composition, and their energy spectra. In the context of acceleration mechanisms in general, the acceleration mechanism responsible for SEP events, diffusive shock acceleration, is then described in some detail including its predictions for a planar stationary shock, shock modification by the energetic particles, and wave excitation by the accelerating ions. Finally, some complexities of shock acceleration are addressed, which affect the predictive ability of the theory. These include the role of temporal and spatial variations, the distinction between the plasma and wave compression ratios at the shock, the injection of thermal plasma at the shock into the process of shock acceleration, and the nonlinear evolution of ion-excited waves in the vicinity of the shock.

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Mewaldt, R. A.0000-0003-2178-9111
Additional Information:© 2012 Springer Science+Business Media B.V. Received: 17 April 2012; Accepted: 22 August 2012; Published online: 22 September 2012. The authors wish to acknowledge the hospitality of the International Space Science Institute, the stimulating program of the Workshop on Particle Acceleration in Cosmic Plasmas, and the patience of Dr. Andre Balogh while awaiting this typescript. The contribution of M.A.L. was supported, in part, by NASA grants NNX08AJ13G, NNX11AO97G and NNX12AB32G. The contribution of R.A.M. was sponsored by NASA under grants NNX8AI11G, NNX06AC21G, and under subcontract SA2715-26309 from UC Berkeley under NASA contract NAS5-03131. The contribution of J.G. was supported, in part, by NASA grants NNX11AO64G and NNX10AF24G.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:Particle acceleration; Solar energetic particles; Diffusive shock acceleration
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2013-10
Issue or Number:1-4
Record Number:CaltechAUTHORS:20121219-140306345
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36056
Deposited By: Tony Diaz
Deposited On:20 Dec 2012 23:06
Last Modified:22 Nov 2019 09:58

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