[Table of Contents]

Plasma and Fusion Research

Volume 6, 2402141 (2011)

Regular Articles

Experiments of Plasma Current Start-Up in Tokamak-Helical Hybrid Device TOKASTAR-2
Makoto HASEGAWA, Kozo YAMAZAKI, Hideki ARIMOTO, Tetsutarou OISHI, Kazuhisa BABA, Motoki SUWABE and Tatsuo SHOJI
Department of Energy Engineering and Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8093, Japan
(Received 7 December 2010 / Accepted 17 August 2011 / Published 21 October 2011)


The small device named TOKASTAR-2 has tokamak-helical hybrid coils to generate both configurations independently. We produced pre-ionized plasma with simple toroidal field in this TOKASTAR-2, and the spatial profiles of electron temperature and density were measured, which suggests both fundamental ECR heating process and other heating mechanisms. Within the limitation of static vertical field, around 0.1 kA plasma current was induced with strongly inward shifted configuration observed by the fast camera measurement, which is verified by the TOSCA equilibrium analysis. It was found that the eddy currents on the vacuum chamber prevent the plasma current build-up. The preliminary application of outer helical field was tried and the plasma current reduction was observed. For the optimization of tokamak operation to drive 1 kA plasma current, time-varying vertical field coil currents and eddy currents were evaluated by the TOSCA code, and the necessity of in-vessel vertical field coils was clarified. The pure current-less TOKASTAR configuration will be demonstrated by installing additional helical coils in the future.


TOKASTAR-2, Tokamak, Helical, hybrid configuration, plasma current, pre-ionized plasma, Langmuir probe, ECR (Electron Cyclotron Resonance), UHR (Upper Hybrid Resonance), TOSCA code

DOI: 10.1585/pfr.6.2402141


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This paper may be cited as follows:

Makoto HASEGAWA, Kozo YAMAZAKI, Hideki ARIMOTO, Tetsutarou OISHI, Kazuhisa BABA, Motoki SUWABE and Tatsuo SHOJI, Plasma Fusion Res. 6, 2402141 (2011).