HR: 15:00h
AN: SH53A-05 INVITED     [Abstracts]
TI: Outstanding Puzzles in Shock Acceleration
AU: * Lee, M A
EM: marty.lee@unh.edu
AF: Martin A. Lee, Space Science Center, Morse Hall, UNH, Durham, NH 03824, United States
AB: The association between shocks and energetic particles in the heliosphere is well established. In addition, the theory of diffusive shock acceleration (DSA) has been viewed as a success in describing many features of this association in "events" ranging from planetary bow shocks, to interplanetary traveling shocks and corotating interaction region (CIR) shocks in the solar wind. Nevertheless, a challenging array of observations seems to contradict the predictions of DSA. Several of these contradictions have been listed in the session description. This paper addresses some of these contradictions. They result because our applications of the theory are usually restricted to simplifying assumptions, such as a planar stationary configuration and injection from a single pool of low-energy particles, which are usually not warranted. In addition, the fundamental assumptions of DSA are often violated in Nature, where phase-space distribution functions are not nearly isotropic and spatial diffusive transport is inadequate or difficult to specify. Finally, the process of particle injection at the shock from low energies into the process of shock acceleration, which dictates to a large extent ion composition, is not described by the theory of DSA. These inadequacies appear to account for (most of) the contradictions. Clearly generalizations to the theory of DSA are required.
DE: 2124 Heliopause and solar wind termination
DE: 2139 Interplanetary shocks
DE: 7807 Charged particle motion and acceleration
DE: 7845 Particle acceleration
DE: 7851 Shock waves (4455)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Joint Assembly