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Power & Industrial Systems R & D Division,
Hitachi, Ltd. 7-2-1, Omika-cho, Hitachi-shi, Ibaraki, 319-1221, Japan
K. Asano, M. Otsuka
Hitachi works, Hitachi Ltd. 3-1-1, Saiwai-cho,
Hitachi-shi, Ibaraki, 315, Japan
Abstract. A plasma discharge experiment, measurements and calculations of the
magnetic field in the Hitachi tokamak HT-2 showed that ferritic steel is
available for the vacuum vessel structural material in fusion devices, in
spite of its ferromagnetism. The HT-2 has a stainless steel SS304 vacuum
vessel and F82H plates were added just like a first wall, to simulate a
ferritic vacuum vessel. The vacuum quality was not degraded. About 1500
discharge tries cleaned up the F82H and normal discharges was obtained. The
magnetic field due to the F82H magnetization was small enough that it did not
cause a problem for plasma discharge in the HT-2. Since the field due to the
magnetization is expected to be smaller in large tokamaks than in the HT-2, we
concluded that the ferritic steel can be used as a structural material for
fusion devices.
IAEA 2001
