Publications: paper No 22

Modelling the Solar Wind Interaction With Mercury by a Quasineutral Hybrid Model

E. Kallio and P. Janhunen
Finnish Meteorological Institute, Helsinki, Finland

Annales Geophysicae, Vol. 21, NO. 11, 2133-2145, 2003

abstract Quasineutral hybrid model is a self-consistent modelling approach that includes positively charged particles and an electron fluid. The approach has received an increasing interest in space plasma physic research because it makes it possible to study several plasma physical processes that are difficult or impossible to model by self-consistent fluid models, such as effects associated with ions' finite gyroradius, the velocity difference between different ion species, or the non-Maxwellian velocity distribution function. By now quasineutral hybrid models have been used to study the solar wind interaction with non-magnetised Solar System bodies Mars, Venus, Titan and comets. Localized, two dimensional hybrid model runs have also made to study terrestrial dayside magnetosheath. However, the Hermean plasma environment has not yet been analysed by a global quasineutral hybrid model.

In this paper we present a new quasineutral hybrid model developed to study various processes associated with the Mercury-solar wind interaction. Emphasis is placed on addressing advantages and disadvantages of the approach to study different plasma physical processes near the planet. The basic assumptions of the approach and the algorithms used in the new model are thoroughly presented. Finally some of the first three dimensional hybrid model runs made for Mercury are presented.

The resulting macroscopic plasma parameters and the morphology of the magnetic field demonstrate the applicability of the new approach to study the Mercury-solar wind interaction globally. In addition, the real advantage of the kinetic hybrid model approach is to study the property of individual ions and the study clearly demonstrates the large potential of the approach to address these more detailed issues by quasineutral hybrid model in the future.. 

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