Berlin 2001 – wissenschaftliches Programm
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P: Plasmaphysik
P 1: Magnetic Confinement and Plasma Wall Interaction
P 1.2: Vortrag
Montag, 2. April 2001, 16:45–17:00, 2053
Electric confinement of ions in fusion experiments — •Dirk Naujoks — Max-Planck-Institut für Plasmaphysik, Mohrenstr. 41, D-10117 Berlin, Germany
The problem of charge shielding in magnetized plasmas has been analyzed by means of PIC (particle-in-cell) simulations. The dimensionless parameter ξ=(npl M)/(єo B2) defines the role of the magnetic field B. npl is the plasma density and M is the mass of the plasma ions. For low values of ξ (e.g. strong magnetic field) plasma shielding of perturbing test charges cannot occur. Under the conditions of today’s fusion experiments the electrons are usually tied to the magnetic field lines due to their small gyration radii. The ions have much larger gyration radii and the corresponding parameter ξ is about 1000. For such high values of ξ the effect of the magnetic field is so weak, that only electric forces are of importance. Thus, a small charge imbalance is required to build up an electric field, which confines the ions in the plasma volume. The action of this self-consistent electric field leads to an ion density profile almost equal to the given electron density profile.