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The ablated material of a frozen hydrogen isotope pellet which is injected into a hot tokamak plasma forms a high beta plasmoid. This diamagnetic plasmoid is accelerated to the magnetic low field side of the torus. The high beta plasmoid drift was directly observed by an optical diagnostic with high space and time resolution. Spectroscopic measurements of the emitted light allowed the density and temperature of the ablation cloud, and for the first time also of the drifting plasmoids, to be determined. The experiments give a new insight into the dynamics of the formation of striations during the pellet ablation; these striations cause the separation of the ablated material into a sequence of separated, drifting plasmoids. The influence of the drift on the mass deposition profile for high field side pellet injection is discussed. The plasmoid dynamics even influences the radial pellet motion, most probably owing to a rocket effect. The physical principles of the high beta plasmoid drift are discussed and compared with the experimental observations.

Additional information

Authors: MULLER H W ET AL, Max-Planck-Institut fur Plasmaphysik, EURATOM Association, Garching (DE);MÜLLER H W ET AL, Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (DE)
Bibliographic Reference: An article published in: Nuclear Fusion 42 (March 2002) 301-309
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Record Number: 200214857 / Last updated on: 2002-06-19
Original language: en
Available languages: en