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Analysis of the residual neutral gas during plasma discharges in the tokamak TEXTOR shows considerable amounts of neutral CO and CO(2). Details of these observations have suggested that the CO(2) and part of the CO neutral gas is released from the surfaces by photon-stimulated desorption processes. To prove this suggestion, additional mass spectroscopic measurements have been performed in a chamber vacuum-sealed from the TEXTOR vacuum by a MgF(2)-window which is transparent for wavelengths above about 110 nm. It has been confirmed that CO(2) and CO molecules together with H(2) are released from the walls of the chamber by the photons penetrating from the TEXTOR plasma through the window. The overall desorption rate has been estimated to be between 1.0 E-4 and 1.0 E-5 molecules/photon, and a linear relation between the amount of desorbed molecules and the total radiation from the plasma has been found. The results are discussed in view of the overall impurity release from the walls and limiters of TEXTOR.

Additional information

Authors: PHILIPPS V, Forschungszentrum Jülich GmbH (KFA) (DE);VIETZKE E, Forschungszentrum Jülich GmbH (KFA) (DE);ERDWEG M, Forschungszentrum Jülich GmbH (KFA) (DE);WINTER J, Forschungszentrum Jülich GmbH (KFA) (DE)
Bibliographic Reference: Article: Journal of Nuclear Materials, Vol. 200 (1993) pp. 355-359
Record Number: 199311255 / Last updated on: 1994-11-29
Original language: en
Available languages: en