[Table of Contents]

Plasma and Fusion Research

Volume 7, 2402114 (2012)

Regular Articles

Plasma Potential in Toroidal Devices: T-10, TJ-II, CHS and LHD
Alexander V. MELNIKOV, Carlos HIDALGO1), Takeshi IDO2), Akihiro SHIMIZU2), Akihide FUJISAWA3), Konstantin S. DYABILIN and Sergey E. LYSENKO
Institute of Tokamak Physics, NRC ‘Kurchatov Institute', 123182, Moscow, Russia
1)
Association EURATOM-CIEMAT, 28040, Madrid, Spain
2)
National Institute for Fusion Science, Toki 509-5292, Japan
3)
Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
(Received 9 December 2011 / Accepted 12 June 2012 / Published 13 September 2012)

Abstract

Direct measurements of the electric potential φ, using the Heavy Ion Beam Probing, have been undertaken in the T-10 tokamak, and in the helical devices with various magnetic topology: TJ-II, CHS and LHD. L-mode plasmas were considered. Despite the large differences in machine sizes, heating methods and the topology of the magnetic field, the observed φ shows the striking similarities: (i) Similar magnitudes of Er; (ii) For low densities, ne < 0.5 × 1019 m−3, φ is positive, and an increase in ne is associated with the decrease of positive φ and formation of a negative Er; (iii) For higher densities, ne > (0.5-1)× 1019 m−3 , both φ and Er tends to be negative despite the use of different heating methods: Ohmic and ECR heating in T-10, ECRH and/or NBI in TJ-II, CHS and LHD; (iv) Application of ECRH, causing a rise in Te, results in more positive values for φ and Er. The analysis show that the main features of the φ dependences on the ne and Te agree with neoclassical predictions on the four devices within experimental and simulation precisions.

Keywords

plasma electric potential, radial electric field, HIBP, tokamak, stellarator, neoclassical theory

DOI: 10.1585/pfr.7.2402114

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This paper may be cited as follows:

Alexander V. MELNIKOV, Carlos HIDALGO, Takeshi IDO, Akihiro SHIMIZU, Akihide FUJISAWA, Konstantin S. DYABILIN and Sergey E. LYSENKO, Plasma Fusion Res. 7, 2402114 (2012).