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P: Plasmaphysik

P 8: Plasma-Wand-Wechselwirkung

P 8.3: Vortrag

Dienstag, 19. März 2002, 15:50–16:05, HZO 70

Influence of a local neutral particle source on the plasma boundary in TEXTOR — •B. Unterberg², G. Sergienko¹, S. Brezinsek², A. Pospieszczyk², and M. Lehnen² — ¹Institute for High Temperatures - RAS, Moscow, Russia, Association IVTAN — ²Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, EURATOM Assoziation, Trilateral Euregio Cluster, D-52425 Jülich, Deutschland

The standard method of plasma fuelling in a tokamak is molecular hydrogen (deuterium) puffing into the plasma boundary. To produce a fast plasma density rise, a strong puffing is required which influences not only the edge plasma parameters but also the confinement characteristics of the main plasma. Therefore, both the particle and energy confinement substantinally degradates if strong gas puffing is applied in discharges with improved confinement. The influence of the local puffing onto the plasma edge characteristics will be discussed. Measurements of the plasma parameters in the vicinity of the gas injection location were made by means of molecular and atomic spectroscopy. We deduced from the rotational temperature of the deuterium molecules that the local plasma density can increase by several times with respect to the background edge density. However, the electron temperature remains high enough that local recombination does not occur as determined from the Balmer line series.