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Abstract

Determination of the vertical stray field in the plasma centre produced by poloidal field coils is essential for the control of breakdown and of the horizontal plasma position in tokamaks. Measurement by magnetic probes does not provide satisfactory results since the toroidal field perpendicular to the poloidal one is 30 to 3000 times higher and thus induces error signals. An electron beam technique has been chosen to solve this problem. An electron gun has been specially designed for TEXTOR and implemented for measurements. Magnetic field lines were made visible using the effect of electron movement in magnetic fields and light emission in a gas. Vertical fields were determined from the measured toroidal field and vertical beam displacements. In addition to the measured efficiencies of poloidal field coils, exact values for the field compensation during premagnetisation have been defined. Results have been verified by field calculations and compared with results from plasma breakdown experiments.

Additional information

Authors: NEUBAUER O ET AL., Forschungszentrum Jülich GmbH (KFA) (DE);CHUDNOVSKIJ A, Kurchatov Institute, Moscow (RU)
Bibliographic Reference: Report: JÜL-3032 EN (1995) 20 pp.
Availability: Available from Zentralbibliothek der Forschungszentrum Jülich GmbH, Postfach 1913, 5170 Jülich (DE)
Record Number: 199510596 / Last updated on: 1995-05-03
Category: PUBLICATION
Original language: en
Available languages: en
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