W7-AS: One step of the Wendelstein stellarator line

Journal Article · Fri Jul 15 00:00:00 EDT 2005 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.1927100· OSTI ID:20764397

Wagner, F; Baeumel, S; Baldzuhn, J; Basse, N; Brakel, R; Burhenn, R; Dinklage, A; Dorst, D; Ehmler, H; Endler, M; Erckmann, V; Feng, Y; Gadelmeier, F; Geiger, J; Grigull, P; Hartfuss, H -J; Hartmann, D; Hildebrandt, D; Hirsch, M ^[1]

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1. Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 17491 Greifswald (Germany)

This paper is a summary of some of the major results from the Wendelstein 7-AS stellarator (W7-AS). W7-AS [G. Grieger et al., Phys. Fluids B 4, 2081 (1992)] has demonstrated the feasibility of modular coils and has pioneered the island divertor and the modeling of its three-dimensional characteristics with the EMC3/EIRENE code [Y. Feng, F. Sardei et al., Plasma Phys. Controlled Fusion 44, 611 (2002)]. It has extended the operational range to high density (4x10{sup 20} m{sup -3} at 2.5 T) and high <{beta}> (3.4% at 0.9 T); it has demonstrated successfully the application of electron cyclotron resonance heating (ECRH) beyond cutoff via electron Bernstein wave heating, and it has utilized the toroidal variation of the magnetic field strength for ion cyclotron resonance frequency beach-wave heating. In preparation of W7-X [J. Nuehrenberg et al., Trans. Fusion Technol. 27, 71 (1995)], aspects of the optimization concept of the magnetic design have been successfully tested. W7-AS has accessed the H-mode, the first time in a 'non-tokamak' and has extended H-mode operation toward high density by the discovery of the high-density H-mode (HDH), characterized by H-mode energy and L-mode-level impurity confinement. In the HDH-mode quasisteady state operation is possible close to operational limits without noticeable degradation in the plasma properties. High-{beta} phases up to t{sub pulse}/{tau}{sub E}=65 have been achieved, which can already be taken as an indication of the intrinsic stellarator capability of steady-state operation. Confinement issues will be discussed with emphasis on the similarities to tokamak confinement (general transport properties, H-mode transition physics) but also with respect to distinct differences (no confinement degradation toward operational boundaries, positive density scaling, lack of profile resilience, no distinct isotope effect, H-mode operational window). W7-AS turned out to be an important step in the development of the Wendelstein stellarator line towards an independent fusion power plant concept.

• OSTI ID: 20764397
• Journal Information: Physics of Plasmas, Vol. 12, Issue 7; Other Information: DOI: 10.1063/1.1927100; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BERNSTEIN MODE
CHARGED-PARTICLE TRANSPORT
COMPUTERIZED SIMULATION
DIVERTORS
ECR HEATING
ELECTRONS
H-MODE PLASMA CONFINEMENT
HIGH-BETA PLASMA
ION CYCLOTRON-RESONANCE
ISOTOPE EFFECTS
L-MODE PLASMA CONFINEMENT
MAGNETIC FIELDS
PLASMA DENSITY
PLASMA IMPURITIES
PLASMA INSTABILITY
PLASMA SIMULATION
PLASMA WAVES
RF SYSTEMS
STEADY-STATE CONDITIONS
THERMONUCLEAR POWER PLANTS
THREE-DIMENSIONAL CALCULATIONS
TOKAMAK DEVICES
WENDELSTEIN-7 STELLARATOR