Barghouty, A. F. and Mewaldt, R. A. (2000) Simulation of Charge-Equilibration and Acceleration of Solar Energetic Ions. In: Acceleration and Transport of Energetic Particles Observed in the Heliosphere. AIP Conference Proceedings (528). American Institute of Physics , Melville, N.Y., pp. 71-78. ISBN 1-56396-951-3 http://resolver.caltech.edu/CaltechAUTHORS:20111123-080938173
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Recent measurements of the mean ionic charge states of solar energetic iron and silicon by SAMPEX and ACE during the large solar events of 1992 November 1 and 1997 November 6 show a mean ionic charge that increases with energy. This feature has implications for the use of the observed charge state as a probe of the coronal electron temperature and density, as well as for models of ion acceleration and transport in the coronal plasma. In this paper, we show results of a nonequilibrium model for the mean ionic charge that includes shock-induced acceleration in addition to charge-changing processes. The model is able to reproduce the general features observed without, however, specifying uniquely the acceleration time and the plasma electron density. Based on our simulations for iron and silicon for the 1992 and 1997 events, and assuming a characteristic shock-acceleration time of ~10 sec, our model suggests an equilibration-acceleration site at heights ~1 solar radius above the solar surface, a density ~10^9 cm^(–3), and an electron temperature ~1–1.33 MK. For ions with kinetic energy ≳ 30 MeV/nucleon we estimate the amount of coronal material the ions traverse to be ~100 µg/cm^2.
|Item Type:||Book Section|
|Additional Information:||© 2000 American Institute of Physics. Issue Date: 15 September 2000. Work is supported by NSF grant 9810653 and NASA-JOVE NAG8-1208 and by NASA grants NAS5-30704 and NAG5-6912 at Caltech. A.F.B. thanks Prof. M. Yoshimori for stimulating discussions and Dr. Christina Cohen for valuable help with SOHO and ACE data.|
|Group:||Space Radiation Laboratory|
|Subject Keywords:||solar cosmic ray particles, positive ions, electric charge, acceleration, shock wave effects, cosmic ray propagation, solar radiation, astrophysical plasma, plasma temperature, ion density|
|Classification Code:||PACS: 96.40.Fg; 96.50.Pw|
|Official Citation:||Simulation of charge-equilibration and acceleration of solar energetic ions A. F. Barghouty and R. A. Mewaldt, AIP Conf. Proc. 528, 71 (2000), DOI:10.1063/1.1324283|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||23 Nov 2011 16:28|
|Last Modified:||04 Mar 2013 22:57|
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