Studying Transport of Heavy ions in SEP events
Abstract
In Solar Energetic Particle (SEP) events, particles are accelerated to energies of > 100 MeV/nuc near the Sun and then propagate to 1 AU. Transport of these energetic particles in the solar wind is subject to pitch angle scattering by solar wind MHD turbulence. The observed time intensity profile, particle spectrum, and anisotropy at 1 AU depend on the injected particle profile, the interplanetary turbulence, its spectral form and its radial evolution. We have developed a direct Monte-Carlo simulation that follows the transport of SEPs. The code follows the Guiding Center of charged particles in a pre-specified Parker spiral magnetic field and includes effects such as adiabatic cooling, pitch angle scatter and solar wind convection. In modeling the change of particle pitch angle, we use the framework of the Quasi Linear Theory and treat the pitch angle diffusion using a stochastic differential equation method.
Use this code, Helium, CNO and Iron ions are studied, the Q/A dependence of particle spectrum and time intensity profiles are obtained. Our model can be used to fit specific SEP events to obtain the corresponding interplanetary MHD turbulence profile. We expect this profile vary significantly from event to event. Therefore, SEPs provide an indirect means of probing the solar wind MHD turbulence, from close to the Sun to 1 AU.- Publication:
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Solar Heliospheric and INterplanetary Environment (SHINE 2010)
- Pub Date:
- July 2010
- Bibcode:
- 2010shin.confE..29L