34th Solar Physics Division Meeting, June 2003
Session 16 Flares and Microflares II
Poster, Wednesday, June 18, 2003, 3:30-5:00pm, Mezzanine

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[16.05] Stochastic Acceleration of Ions and Electrons by Parallel Propagating Turbulent Plasma Waves

S. Liu (CSSA, Dept. of Physics, Stanford Univ.), V. Petrosian (Also Dept. of Applied Physics, Stanford Univ.)

Studies of ion acceleration are usually done with Alfven waves and fast waves. However, in the case of strongly magnetized plasma like in solar flares, exact solutions incorporating the dispersion relation valid over a broad spectrum of turbulence not only are important in detailing the acceleration of particles from a thermal background, but also may be essential to explain certain "abnormalities" such as the interplanetary heavy ion distribution or energy partition between high energy electrons and protons observed during the impulsive phase of solar flares. In this paper, we study the stochastic acceleration of electrons and ions by parallel propagating waves in a cold magnetized electron-proton plasma. Although contribution to acceleration rate from Fokker-Planck coefficients D\mu p and D\mu \mu are typically small for relativistic particles, their effect on low energy particles is substantial. This is especially the case for ions because it can only be accelerated by left-handed proton cyclotron waves at very low energies. The lack of interaction with right-handed waves makes the ion acceleration rate decrease sharply with the decrease of energy near certain critical energy. Its comparison with electron acceleration will be presented. The implications of these results for solar flares phenomena will be discussed.

This study also suggests that the simplest model with homogeneous turbulence and energy equipartition among different wave modes might not account for flares with simultaneous comparable gamma-ray emissions from both electrons and protons. Although it is possible that other wave modes may be able to account for this problem, inhomogeneity of the turbulence and/or absence of energy equipartition among different wave modes can also be feasible solutions. We will discuss constraints on properties of the required turbulence based on this model.

The work at Stanford is supported by NASA grants NAG5-12111, NAG5 11918-1, and SUB2001-402-01 through University of Alabama in Huntsville (PI: J. Miller).


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The author(s) of this abstract have provided an email address for comments about the abstract: liusm@stanford.edu

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