Battarbee, M., Laitinen, Timo Lauri Mikael and Vainio, R. (2011) Heavy-ion acceleration and self-generated waves in coronal shocks. Astronomy & Astrophysics, 535 (-). pp. 1-6. ISSN 0004-6361
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Official URL: http://dx.doi.org/10.1051/0004-6361/201117507
Context. Acceleration in coronal mass ejection driven shocks is currently considered the primary source of large solar energetic particle events.
Aims. The solar wind, which feeds shock-accelerated particles, includes numerous ion populations, which offer much insight into acceleration processes. We present first simulations of shock-accelerated minor ions, in order to explore trapping dynamics and acceleration timescales in detail.
Methods. We have simulated diffusive shock acceleration of minor ions (3He2+, 4He2+, 16O6+ and 56Fe14+) and protons using a Monte Carlo method, where self-generated Alfvénic turbulence allows for repeated shock crossings and acceleration to high energies.
Results. We present the effect of minor ions on wave generation, especially at low wavenumbers, and show that it is significant. We find that maximum ion energy is determined by the competing effects of particle escape due to focusing in an expanding flux tube and trapping due to the amplified turbulence. We show the dependence of cut-off energy on the particle charge to mass ratio to be approximately (Q/A)1.5.
Conclusions. We suggest that understanding the acceleration of minor ions at coronal shocks requires simulations which allow us to explore trapping dynamics and acceleration timescales in detail, including evolution of the turbulent trapping boundary. We conclude that steady-state models do not adequately describe the acceleration of heavy ions in coronal shocks.
|Uncontrolled Keywords (separate with ;):||acceleration of particles; turbulence; Sun: coronal mass ejections (CMEs;|
|Subjects:||Physical sciences > Astronomy|
Physical sciences > Physics
|Schools:||Faculty of Science and Technology > School of Physical Sciences and Computing > Jeremiah Horrocks Institute|
|Deposited By:||Nuala Jones|
|Deposited On:||05 Mar 2013 12:05|
|Last Modified:||09 Aug 2016 15:17|
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