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Tokamak plasmas are in a state of permanent reorganization due to strong MHD activity. Central MHD phenomena can be observed with pinhole cameras in which silicon wafers with additional foils record soft X-ray emission from the plasma along many chords with high temporal resolution. To separate the repetition time and the characteristic radius of various MHD phenomena such as sawteeth and, in H-mode, ELMs from these chord-integrated measurements, the method of singular-value decomposition is of great value. Moreover, the helical (1, 1) MHD mode is analysed in great detail. In a zeroth approximation, the minimum and maximum values of the spatial eigenvectors are used to determine the radius of the q = 1 surface. In a next step, a model of the (1, 1) mode is developed which evaluates the line-integrated signals in elliptical geometry. This serves for interpolation and thereby improves spatial resolution. Finally, the information is added into a fast equilibrium reconstruction code which leads to improved current profile identification.

Additional information

Authors: BESSENRODT-WEBERPALS M ET AL, Max-Planck-Institut für Plasmaphysik, Garching bei München (DE)
Bibliographic Reference: Article: Plasma Physics and Controlled Fusion, Vol. 38 (1996) pp. 1543-1559
Record Number: 199611349 / Last updated on: 1996-11-21
Original language: en
Available languages: en
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