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Abstract

An understanding of the physics of neoclassical tearing modes (NTMs) gained through experimentation and modelling at ASDEX Upgrade is presented. The onset beta{N} for NTM is found to be proportional to the normalized ion gyroradius rho{*} and independent of the normalized collisionality v{*} for a wide range of v{*}.

This scaling is in accordance with both polarization current and X(normal)/X(perpendicular) model if for the latter the heat flux limit on parallel heat conductivity is taken into account. Analysis of the structure and dynamics of NTMs validates the negative Delta{prime}. Complete stabilization using ECCD has been demonstrated at beta{N} = 2.5 and with about 10% of the total heating power. The results are in good qualitative agreement with modelling using the Rutherford equation and in quantitative agreement with a two-dimensional non-linear cylindrical tearing mode code. A precise positioning of the ECCD microwave beam, achieved so far by feed-forward variation of B{t}, is required for efficient stabilization.

Additional information

Authors: ZOHM H, Max-Planc Institut fur Plasmaphysik, Euratom Association, Boltzmannstrausse 2, D-85748 Garching bei Munchen (DE);GUDE A, Max-Planc Institut fur Plasmaphysik, Euratom Association, Boltzmannstrausse 2, D-85748 Garching bei Munchen (DE);LEUTERER F, Max-Planc Institut fur Plasmaphysik, Euratom Association, Boltzmannstrausse 2, D-85748 Garching bei Munchen (DE);MARASCHEK M, Max-Planc Institut fur Plasmaphysik, Euratom Association, Boltzmannstrausse 2, D-85748 Garching bei Munchen (DE);SUTTROP W, Max-Planc Institut fur Plasmaphysik, Euratom Association, Boltzmannstrausse 2, D-85748 Garching bei Munchen (DE);YU Q, Max-Planc Institut fur Plasmaphysik, Euratom Association, Boltzmannstrausse 2, D-85748 Garching bei Munchen (DE);ASDEX UPGRADE TEAM, Max-Planc Institut fur Plasmaphysik, Euratom Association, Boltzmannstrausse 2, D-85748 Garching bei Munchen (DE);ECRH GROUP (AUG), Max-Planc Institut fur Plasmaphysik, Euratom Association, Boltzmannstrausse 2, D-85748 Garching bei Munchen (DE);GANTENBEIN G, Institut fur Plasmaforschung, Stuttgart (DE);GUNTER S, Institut fur Plasmaforschung, Stuttgart (DE);MESKAT J, Institut fur Plasmaforschung, Stuttgart (DE)
Bibliographic Reference: Article: Nuclear Fusion Vol 41 (2001), pp. 197-202
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