HR: 14:45h
AN: SH53A-04 INVITED     [Abstracts]
TI: Deviations From the Predictions of Standard Diffusive Shock Acceleration
AU: * Jokipii, J R
EM: jokipii@lpl.arizona.edu
AF: Department of Planetary Sciences University of Arizona, 1629 E. University Blvd, Tucson, AZ 85721, United States
AU: Giacalone, J
EM: giacalon@lpl.arizona.edu
AF: Department of Planetary Sciences University of Arizona, 1629 E. University Blvd, Tucson, AZ 85721, United States
AB: The mechanism for the acceleration of energetic charged particles remains one of the most important problems of space physics. Diffusive shock acceleration, now almost three decades old, has many attractive features and has become the most popular mechanism. However, it is becoming increasingly clear that in situ observations of energetic particles and shock waves often show very poor agreement with the basic theoretical predictions. Often the energetic-particle enhancements are not observable or occur at a time displaced from the shock passage. Observations from two or more spacecraft show different energetic-particle profiles on the same propagating shock. Statistical studies show poor agreement between the spectrum of energetic particles and the parameters of the shock. Finally, energetic electrons are often observed, but the injection of electrons into diffusive shock acceleration is not understood. One obvious explanation for these discrepancies is that diffusive shock acceleration is not the accelerator of the energetic particles. However, viable alternative mechanisms are so far lacking. Another possibility, diffusive shock acceleration in the presence of broad-band turbulent fluctuations in the upsream fluid will be shown to be a promising solution.
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