scholarly journals Plasma environment of Titan: a 3-D hybrid simulation study

2006 ◽  
Vol 24 (3) ◽  
pp. 1113-1135 ◽  
Author(s):  
S. Simon ◽  
A. Bößwetter ◽  
T. Bagdonat ◽  
U. Motschmann ◽  
K.-H. Glassmeier
Keyword(s):  
Plasma Flow ◽  
Molecular Nitrogen ◽  
Hybrid Simulation ◽  
Spherical Geometry ◽  
Magnetospheric Plasma ◽  
Simulation Code ◽  
Plasma Environment ◽  
Ion Production ◽  
Solar Uv ◽  
Magnetohydrodynamic Models

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.

scholarly journals Three-dimensional multispecies hybrid simulation of Titan's highly variable plasma environment

2007 ◽  
Vol 25 (1) ◽  
pp. 117-144 ◽  
Author(s):  
S. Simon ◽  
A. Boesswetter ◽  
T. Bagdonat ◽  
U. Motschmann ◽  
J. Schuele
Keyword(s):  
Plasma Flow ◽  
Flow Direction ◽  
Three Dimensional ◽  
Hybrid Simulation ◽  
Slight Modification ◽  
Magnetospheric Plasma ◽  
Particle Model ◽  
Tail Region ◽  
Simulation Code ◽  
Ion Species

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.

scholarly journals Real-time 3-D hybrid simulation of Titan's plasma interaction during a solar wind excursion

2009 ◽  
Vol 27 (9) ◽  
pp. 3349-3365 ◽  
Author(s):  
S. Simon
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Real Time ◽  
Plasma Flow ◽  
Time Scale ◽  
Hybrid Simulation ◽  
The Moon ◽  
Plasma Interaction ◽  
Plasma Environment ◽  
The Magnetic Field

Abstract. The plasma environment of Saturn's largest satellite Titan is known to be highly variable. Since Titan's orbit is located within the outer magnetosphere of Saturn, the moon can leave the region dominated by the magnetic field of its parent body in times of high solar wind dynamic pressure and interact with the thermalized magnetosheath plasma or even with the unshocked solar wind. By applying a three-dimensional hybrid simulation code (kinetic description of ions, fluid electrons), we study in real-time the transition that Titan's plasma environment undergoes when the moon leaves Saturn's magnetosphere and enters the supermagnetosonic solar wind. In the simulation, the transition between both plasma regimes is mimicked by a reversal of the magnetic field direction as well as a change in the composition and temperature of the impinging plasma flow. When the satellite enters the solar wind, the magnetic draping pattern in its vicinity is reconfigured due to reconnection, with the characteristic time scale of this process being determined by the convection of the field lines in the undisturbed plasma flow at the flanks of the interaction region. The build-up of a bow shock ahead of Titan takes place on a typical time scale of a few minutes as well. We also analyze the erosion of the newly formed shock front upstream of Titan that commences when the moon re-enters the submagnetosonic plasma regime of Saturn's magnetosphere. Although the model presented here is far from governing the full complexity of Titan's plasma interaction during a solar wind excursion, the simulation provides important insights into general plasma-physical processes associated with such a disruptive change of the upstream flow conditions.

scholarly journals Physics of the Ion Composition Boundary: a comparative 3-D hybrid simulation study of Mars and Titan

2007 ◽  
Vol 25 (1) ◽  
pp. 99-115 ◽  
Author(s):  
S. Simon ◽  
A. Boesswetter ◽  
T. Bagdonat ◽  
U. Motschmann
Keyword(s):  
Solar Wind ◽  
Plasma Flow ◽  
Dynamic Pressure ◽  
Hybrid Simulation ◽  
Ion Composition ◽  
Simulation Code ◽  
Ambient Flow ◽  
Planetary Ionosphere ◽  
Mach Numbers ◽  
Characteristic Features

Abstract. The plasma environments of Mars and Titan have been studied by means of a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas ion dynamics are covered by a kinetic approach. As neither Mars nor Titan possesses a significant intrinsic magnetic field, the upstream plasma flow interacts directly with the planetary ionosphere. The characteristic features of the interaction region are determined as a function of the alfvénic, sonic and magnetosonic Mach number of the impinging plasma. For the Martian interaction with the solar wind as well as for the case of Titan being located outside Saturn's magnetosphere in times of high solar wind dynamic pressure, all three Mach numbers are larger than 1. In such a scenario, the interaction gives rise to a so-called Ion Composition Boundary, separating the ionospheric plasma from the ambient flow and being highly asymmetric with respect to the direction of the convective electric field. The formation of these features is explained by analyzing the Lorentz forces acting on ionospheric and ambient plasma particles. Titan's plasma environment is highly variable and allows various different combinations of the three Mach numbers. Therefore, the Ion Composition Boundary may vanish under certain circumstances. The relevant physical mechanism is illustrated as a function of the Mach numbers in the upstream plasma flow.

scholarly journals Plasma environment of magnetized asteroids: a 3-D hybrid simulation study

2006 ◽  
Vol 24 (1) ◽  
pp. 407-414 ◽  
Author(s):  
S. Simon ◽  
T. Bagdonat ◽  
U. Motschmann ◽  
K.-H. Glassmeier
Keyword(s):  
Solar Wind ◽  
Three Dimensional ◽  
Hybrid Simulation ◽  
Interaction Region ◽  
Bow Shock ◽  
The Other ◽  
Simulation Code ◽  
Kinetic Effects ◽  
Intrinsic Magnetic Moment ◽  
The One

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.

Vortices in magnetospheric plasma flow

1978 ◽  
Vol 5 (12) ◽  
pp. 1059-1062 ◽  
Author(s):  
E. W. Hones ◽  
G. Paschmann ◽  
S. J. Bame ◽  
J. R. Asbridge ◽  
N. Sckopke ◽  
...  
Keyword(s):  
Plasma Flow ◽  
Magnetospheric Plasma

Comparison of the influence of 2D and 3D geometry of the main chamber on plasma parameters in the SOL of ASDEX Upgrade

2021 ◽  
Author(s):  
Lennart Bock ◽  
Dominik Brida ◽  
Michael Faitsch ◽  
Klaus Schmid ◽  
Tilmann Lunt
Keyword(s):  
Plasma Flow ◽  
Neutral Particle ◽  
3D Structure ◽  
Main Chamber ◽  
Plasma Parameters ◽  
Simulation Code ◽  
Particle Distributions ◽  
Low Field ◽  
3D Geometry ◽  
Wall Geometry

Abstract In this paper the influence of toroidally asymmetric wall features on plasma solutions for ASDEX Upgrade is investigated by using the 3D scrape-off-layer simulation code EMC3-EIRENE. A comparison of simulation results in a 2D case with a toroidally symmetric first wall and divertor and a 3D case that differs from the 2D setup by including the 3D structure of the poloidal rib-limiters on the low field side of ASDEX Upgrade, highlights notable differences in the main chamber neutral particle distributions, ionisation sources and plasma flow patterns. Both neutral particle distribution and ionisation sources extend poloidally further upwards at the outer mid-plane in the 3D case and the plasma flow is globally influenced by the 3D wall features. Both simulations are conducted with identical input parameters to isolate the influence of wall geometry from other factors. By analysing the transport of neutrals from different poloidal locations it was possible to explain the observed discrepancies by different transport paths for recycled neutrals from the divertor region, only accessible in the 3D version of the wall geometry. Together with observed differences in fall-off lengths for plasma flow and electron temperature at the outer mid-plane, presented results are of key importance for interpreting global impurity migration experiments.

THE CONDITION OF THE UPPER ATMOSPHERE BASED ON THE ELECTRON DENSITY PROFILES OF THE F REGION

1966 ◽  
Vol 44 (1) ◽  
pp. 175-205 ◽  
Author(s):  
Nobuo Matuura
Keyword(s):  
Electron Density ◽  
Molecular Nitrogen ◽  
Dissociative Recombination ◽  
Atmospheric Parameters ◽  
Density Profiles ◽  
Density Distributions ◽  
F Region ◽  
Recombination Processes ◽  
Ion Production ◽  
Electron Density Profiles

The upper atmospheric parameters that control the daytime electron density distributions in the F1 region have been determined with the use of N(h) profiles. The analysis is based on the photochemical equilibrium state in which ion production is given by the ionization of molecular nitrogen and/or molecular oxygen as well as of atomic oxygen, and ionization loss is controlled by charge transfer and dissociative recombination processes. The variations of the upper atmospheric parameters with season, solar activity, and magnetic disturbances have been obtained, and their relations to the behavior of the F1 and F2 layers have been examined.

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