Ion distributions upstream and downstream of the Earth's bow shock: first results from Vlasiator

Abstract

Abstract.A novel hybrid-Vlasov code, Vlasiator, is developed for global simulations of magnetospheric plasma kinetics. The code is applied to model the collisionless bow shock on scales of the Earth's magnetosphere in two spatial dimensions and three dimensions in velocity space retrieving ion distribution functions over the entire foreshock and magnetosheath regions with unprecedented detail. The hybrid-Vlasov approach produces noise-free uniformly discretized ion distribution functions comparable to those measured in situ by spacecraft. Vlasiator can reproduce features of the ion foreshock and magnetosheath well known from spacecraft observations, such as compressional magnetosonic waves generated by backstreaming ion populations in the foreshock and mirror modes in the magnetosheath. An overview of ion distributions from various regions of the bow shock is presented, demonstrating the great opportunities for comparison with multi-spacecraft observations.

Vlasiator: First global hybrid-Vlasov simulations of Earth's foreshock and magnetosheath

“…The results here as well as in Pokhotelov et al (2013) show that Vlasiator is robust, and can be used for global five-dimensional simulations (two in ordinary space, three in velocity space). The results suggest that Vlasiator is able to reproduce the key features of solar wind-magnetosphere interactions such as the collisionless bow shock, the ion foreshock and the magnetosheath.…”

“…This can lead to ion/ion beam instabilities which grow and generate waves in the foreshock region. We investigate the ion/ion righthand resonant beam instability in the regime relevant to the global magnetospheric simulations presented in Section 5 and in Pokhotelov et al (2013).…”

“…An experimental version of Vlasiator that runs on graphics processing units has also been presented earlier . A verification study of the code in simulations of plasma wave dispersion was presented by Kempf et al (2013) and a short presentation of first magnetospheric simulation results is given in Pokhotelov et al (2013).…”

On the Importance of Spatial and Velocity Resolution in the Hybrid-Vlasov Modeling of Collisionless Shocks

“…Vlasiator is the first hybrid-Vlasov model to have been applied to model the terrestrial magnetosphere at global scales, albeit in a 2D-3V reduced configuration so far [30,[43][44][45][46][47][48][49]. The purpose of this work is to provide a benchmark of the behavior of a hybrid-Vlasov model when varying several key numerical parameters.…”

The Near-Saturn Magnetic Field Environment

“…The advantage of the hybrid-Vlasov approach is its ability to produce noise-free ion distribution functions comparable to those obtained by spacecraft measurements [e.g. Pokhotelov et al (2013)]. …”