Modelling of Solar Wind Plasma Turbulence for Space Missions of ESA and NASA

Abstract

The space between planets, stars and galaxies seems to be empty but it is not. It is completely filled with ionised gas called plasma. In our interplanetary neighbourhood this plasma is launched by the Sun. This continuous stream of solar particles interstratified by the interplanetary magnetic field got the name solar wind. It carries a lot of information from the Sun and it is a unique laboratory to study fundamental physics. The solar wind develops quickly into a turbulent state but the driver for this development is far from complete understanding. Especially multi spacecraft missions supported by high performance computer simulations allow a remarkable progress in turbulence physics. The picture of plasma turbulence in the interplanetary space can be now extended in two fashions by means of the numerical parallelised simulation codes. One is the extension to the fifth dimension by including the time or radial evolution of the turbulent state of the solar wind, i.e. the energy spectrum as a function of wave vectors, frequencies, and radial distance or elapsed time from the Sun. The other extension is a wider coverage of scales ranging from fluid treatment of plasmas (10,000 km or larger) down to the kinetic scales of the ion gyroradius (about 100 km). For this purpose the turbulence is generated by DNS (direct numerical simulation) using hybrid - PIC (Particle-In-Cell) codes. The spatial structure of plasma turbulence and its temperature dependence is obtained by incorporating the hybrid plasma code A.I.K.E.F. into direct numerical simulation of astrophysical kinetic turbulence. The resulting ion-scale turbulence is related to the solar wind distance from the Sun by using a mapping procedure