Abstract
There is substantial evidence suggesting that energetic particles
observed in "gradual" solar energetic particle events are accelerated at
shock waves driven out of the corona by coronal mass ejections (CMEs).
We present a model of particle acceleration at interplanetary shock
waves, assumed to be driven by CMEs, in which the upstream wave
intensity, driven by the accelerated particles, is calculated
self-consistently using the steady-state solution to the wave growth
equation. This then allows for the self-consistent calculation of the
momentum dependent spatial diffusion coefficient which ultimately
governs both the acceleration and subsequent evolution of the energetic
particles. The model is consequently applicable to shock waves of
arbitrary strength, a significant improvement on previous models which
were generally only valid for very strong shock waves. The model is able
to calculate minimum and maximum particles energies as the shock
propagates out into the solar wind and can determine time-dependent
downstream spectra. The spectra of particles escaping into the
relatively undisturbed upstream medium is also calculated and in future
will be used as input to a detailed transport model to determine
upstream spectra and intensity profiles. Although we do not compare the
results with any individual observations, the model is able to reproduce
some of the observed features of "gradual" SEP events. The
self-consistent calculation of the upstream wave intensity will in
future allow this model to be extended to consider the acceleration of
particles of various charge states and masses.
Original language | English |
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Pages (from-to) | 1369 |
Journal | Journal of Geophysical Research |
Volume | 108 |
Publication status | Published - 1 Oct 2003 |
Keywords / Materials (for Non-textual outputs)
- Interplanetary Physics: Energetic particles
- solar
- Solar Physics
- Astrophysics
- and Astronomy: Coronal mass ejections
- Interplanetary Physics: Interplanetary shocks
- Space Plasma Physics: Shock waves
- Space Plasma Physics: Waves and instabilities
- coronal mass ejections (CMEs)
- CME-driven shocks
- particle acceleration
- solar energetic particles
- diffusive shock acceleration