scholarly journals Three-dimensional hybrid simulation of magnetized plasma flow around an obstacle

1999 ◽  
Vol 51 (5) ◽  
pp. 383-393 ◽  
Author(s):  
Hironori Shimazu
2007 ◽  
Vol 25 (1) ◽  
pp. 117-144 ◽  
Author(s):  
S. Simon ◽  
A. Boesswetter ◽  
T. Bagdonat ◽  
U. Motschmann ◽  
J. Schuele

Abstract. The interaction between Titan's ionosphere and the Saturnian magnetospheric plasma flow has been studied by means of a three-dimensional (3-D) hybrid simulation code. In the hybrid model, the electrons form a mass-less, charge-neutralizing fluid, whereas a completely kinetic approach is retained to describe ion dynamics. The model includes up to three ionospheric and two magnetospheric ion species. The interaction gives rise to a pronounced magnetic draping pattern and an ionospheric tail that is highly asymmetric with respect to the direction of the convective electric field. Due to the dependence of the ion gyroradii on the ion mass, ions of different masses become spatially dispersed in the tail region. Therefore, Titan's ionospheric tail may be considered a mass-spectrometer, allowing to distinguish between ion species of different masses. The kinetic nature of this effect is emphasized by comparing the simulation with the results obtained from a simple analytical test-particle model of the pick-up process. Besides, the results clearly illustrate the necessity of taking into account the multi-species nature of the magnetospheric plasma flow in the vicinity of Titan. On the one hand, heavy magnetospheric particles, such as atomic Nitrogen or Oxygen, experience only a slight modification of their flow pattern. On the other hand, light ionospheric ions, e.g. atomic Hydrogen, are clearly deflected around the obstacle, yielding a widening of the magnetic draping pattern perpendicular to the flow direction. The simulation results clearly indicate that the nature of this interaction process, especially the formation of sharply pronounced plasma boundaries in the vicinity of Titan, is extremely sensitive to both the temperature of the magnetospheric ions and the orientation of Titan's dayside ionosphere with respect to the corotating magnetospheric plasma flow.


1998 ◽  
pp. 209-210
Author(s):  
Y. Suzuki ◽  
T.-H. Watanabe ◽  
A. Kageyama ◽  
T. Sato ◽  
T. Hayashi

2006 ◽  
Vol 24 (1) ◽  
pp. 407-414 ◽  
Author(s):  
S. Simon ◽  
T. Bagdonat ◽  
U. Motschmann ◽  
K.-H. Glassmeier

Abstract. The interaction of a magnetized asteroid with the solar wind is studied by using a three-dimensional hybrid simulation code (fluid electrons, kinetic ions). When the obstacle's intrinsic magnetic moment is sufficiently strong, the interaction region develops signs of magnetospheric structures. On the one hand, an area from which the solar wind is excluded forms downstream of the obstacle. On the other hand, the interaction region is surrounded by a boundary layer which indicates the presence of a bow shock. By analyzing the trajectories of individual ions, it is demonstrated that kinetic effects have global consequences for the structure of the interaction region.


2006 ◽  
Vol 24 (3) ◽  
pp. 1113-1135 ◽  
Author(s):  
S. Simon ◽  
A. Bößwetter ◽  
T. Bagdonat ◽  
U. Motschmann ◽  
K.-H. Glassmeier

Abstract. Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.


Sign in / Sign up

Export Citation Format

Share Document