Abstract Selected aspects of energetic (>35 keV) ion acceleration processes in three regions of the heliosphere are reviewed: at interplanetary travelling shocks near 1 AU, in the outer heliosphere and in cometary environments. Clear examples of diffusive acceleration events at quasi-parallel shocks as well as of shock drift acceleration events at quasi-perpendicular shocks near 1 AU have been found. Observations of both individual events and statistical analyses of many events are discussed in the framework of current theoretical models. Specific attention is drawn to the question of ‘seed particles’ for shock-associated events and to the significant number of shocks passing through an ambient interplanetary particle population without affecting it. In the second part of the paper selected observations of particle acceleration processes in the outer heliosphere are discussed, specifically the latitudinal gradient in the energetic ion intensity of shock-acceleration events, derived from Voyager data, and signatures for ‘local’ acceleration of MeV protons, discovered by Pioneer 10. Finally the in-situ observations at comet Giacobini-Zinner and Halley in 1985 and 1986 which have provided clear evidence of ion acceleration processes in the turbulent cometary environment, are placed in the context of current model predictions.
Charged particle acceleration processes in the interplanetary medium
Advances in Space Research ; 9 , 4 ; 179-190
1989-01-01
12 pages
Article (Journal)
Electronic Resource
English
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