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P: Plasmaphysik

P 8: Magnetic Confinement and Plasma Technology (Poster Session)

P 8.12: Poster

Montag, 2. April 2001, 12:30–15:00, AT2

Measurement of magnetic fluctuations by means of a multiple Hall probe in TEXTOR-94 — •G. Mank¹, I. Duran², K.H. Finken¹, and G. van Oost³ — ¹Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, EURATOM Ass., 52425 Jülich, Germany — ²Institute of Plasma Physics, Ass. EURATOM-IPP.CR, 18221 Praha 8, Czech Republic — ³Ghent University, Belgium

A multiple Hall probe diagnostic has been tested in the tokamak TEXTOR-94. Up to 9 Hall probes for multidimensional measurements can be mounted on a probe head which is inserted into the plasma edge. The Hall probe set up is air cooled and shielded by a boron nitride head. The absolute sensitivity is 10e-4 allowing the measurement of perturbation fields of less than 0.1 mT for frequencies in the range from several 100 Hz up to 80 kHz. The advantages of such a system are the compactness and plainness. Frequency spectra have been measured during strong mode activity as e.g. during disruptions. The magnetic turbulence level for the radial and poloidal component has been investigated using fast Fourier analysis. The frequency spectra show the magnetic perturbation due to the precursors of the sawtooth activity. The change of the frequency spectra during neon injection into radiatively improved mode discharges is clearly observable.