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Development of Langmuir Probes on Divertor Cassettes in JT-60SA

Masakatsu FUKUMOTO, Shinji SAKURAI, Nobuyuki ASAKURA¹⁾ and Kiyoshi ITAMI

Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan

1)

Japan Atomic Energy Agency, Rokkasho, Aomori 039-3212, Japan

(Received 10 May 2013 / Accepted 28 August 2013 / Published 15 November 2013)

Abstract

Langmuir probes installed in the lower divertor region under high heat flux have been developed and manufactured for JT-60SA. A probe electrode with a head having a rooftop shape is made of a carbon fiber composite and can withstand heat fluxes of up to 10 MW/m² for 5 s and 1 MW/m² for 100 s. This has been achieved by increasing the volume of the probe electrode that is not directly exposed to the plasma. To minimize the reduction of the heat removal performance of the divertor, the Langmuir probes are installed in toroidal gaps with widths of 10 mm between the divertor cassettes, without embedding them in the divertor tiles. Aluminum oxide coatings have been applied to insulate the probe electrodes from the divertor cassettes and to limit the toroidal thickness to 8 mm. Brazing of the nickel connectors to the probe electrodes has reduced the toroidal thickness of the Langmuir probes. A minimum spatial resolution of 13.5 mm has been achieved to the Langmuir probes installed on the inner and outer divertor targets.

Copyright (c) 2013 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

Langmuir probe, Al₂O₃ coating, brazing, JT-60SA, divertor plasma, plasma equilibrium

DOI: 10.1585/pfr.8.1405153

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This paper may be cited as follows:

Masakatsu FUKUMOTO, Shinji SAKURAI, Nobuyuki ASAKURA and Kiyoshi ITAMI, Plasma Fusion Res. 8, 1405153 (2013).