Research at our Institute: Simulation of the Plasma Interaction
In connection with the magnetometer experiment (MAG) on board of the Cassini spacecraft the Institute of Geophysics and Meteorology at the University of Cologne deals with the development of models in order to describe the interesting plasma interaction of Titan.
The model of Mücke-Herzberg is a one-dimensional magnetohydrodynamical (MHD) model (i.e. ions and electrons are treated as fluids). It describes the cross-over of the magnetospheric plasma to the plasma in Titan's ionosphere. The dynamical variables are the velocity, number density, and temperature (of ions and electrons), and the magnetic field. The model includes 24 ion species, explicitely considering their chemical reactions among each other and with the neutral gas. The production and loss of ions appear as source and sink terms in the continuity equations of every species.
As a result the deceleration process of the fast magnetospheric plasma as it enters Titan's dense atmosphere is simulated. In addition the development of an ionopause and the position and structure of the ionospheric peak can be observed within the model.
Another approach to enlighten the fascinating dynamics of Titan's plasma interaction is the three-dimensional model, also realized at our institute. The plasma is treated as a electron fluid and ion fluid consisting of only one ion species with an average mass. This method is called two-fluid MHD. The objective of this simulation is the investigation of the 3D features of Titan's plasma interaction e.g. structures in the magnetic field or the spatial structure of the ionosphere.
First results are presented in the following thesis (in German):
Mücke-Herzberg, D.
Ein eindimensionales Multiionen-MHD-Modell der Ionosphärendynamik von Titan. Dissertation, Universität zu Köln (published in: Mitteilungen aus dem Institut für Geophysik und Meteorologie der Universität zu Köln, Heft 124), 1998
Authors: Heiko Backes, Dorothea Mücke-Herzberg