HR: 08:20h
AN: SH31B-02 INVITED    [Abstracts]
TI: Interactions of Energetic Particles and Heliospheric Turbulence: Issues and Challenges
AU: * Jokipii, J R
EM: jokipii@lpl.arizona.edu
AF: University of Arizona Planetary Sciences and Astronomy, Kuiper Space Sciences rm 411, Tucson, AZ 85721, United States
AB: The transport and acceleration of energetic charged particles in collisionless astrophysical plasmas is determined significantly by their interactions with turbulence. It has realized for some time that the simple, intuitive "billiard-ball" scattering picture whereby the particles are "scattered" by magnetic fluctuations is inadequate. The spatial transport depends on the nature of the turbulence at all scales, ranging from the small scales of the order of the energetic particle gyro-radius to the outer or coherence scale, which determines the field-line meandering or random walk. Spacecraft observations require that the cross-field transport be much larger than suggested by the simple scattering picture. In addition, observations now show that the turbulence itself is more complex than initially supposed. The anisotropy of the turbulence and intermittency effects impact the particle transport in ways that are yet not fully understood. For example, the "dropouts" observed in impulsive solar-energetic-particle events have been interpreted in two quite-different different ways - either as an initial transient effect or as the result of the behavior turbulent field lines themselves. Some recent work has suggested that subdiffusive or superdiffusive transport may occur and explain some energetic-particle observations. The challenges presented by the observations and possible explanations in terms of new ideas will be critically discussed.
DE: 2104 Cosmic rays
DE: 2159 Plasma waves and turbulence
DE: 7859 Transport processes
DE: 7863 Turbulence (4490)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting