Hannover 2010 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 22: Poster: Theory/Modelling II

P 22.4: Poster

Donnerstag, 11. März 2010, 16:00–18:00, Lichthof

Modeling of massive gas injection in tokamaks — •Mikhail Koltunov, Mikhail Tokar, and Michael Lehnen — Institut für Energieforschung -- Plasmaphysik, Forschungszentrum Jülich GmbH, Association FZJ--Euratom, Trilateral Euregio Cluster, Germany

Heat losses and energetic runaway electrons generated by plasma disruptions can lead in future fusion reactors to intolerable wall erosion and mechanical forces on the vessel. In order to soften consequences of disruptions, provide a controllable and safe ending of discharges, and prevent machine damage massive injection of different neutral gases is used.

In this contribution the first modeling results of gas injection impacts on the local plasma behavior are presented. For this purpose a quasi 2-D fluid model is developed to describe the transport of both, very locally injected impurity neutrals and impurity ions generated by ionization, and their effects on the background plasma. The model allows to analyze the main impacts of the injected particles on the plasma caused by the production of electrons by impurity ionization, generation of intensive electric fields, cooling of electrons by radiation losses, friction forces on main ions by coulomb collisions, etc. The modification of the plasma state affects the impurity penetration process itself and this is taken self-consistently into account. One of the important problems discussed in the contribution is the selection of proper boundary conditions for the parallel momentum equations for the main and impurity ions both in the scrape-off layer, where the plasma is bounded by the limiter, and in the confined volume.