The role of plasma-wall interactions in thermal instabilities at the tokamak edge

Tokar, M. Z.; Kelly, F. A.

doi:10.1063/1.1613963

Journal Article

PreJuSER-28960

The role of plasma-wall interactions in thermal instabilities at the tokamak edge

Tokar, M. Z.FZJ* ; Kelly, F. A.FZJ*

2003
American Institute of Physics [S.l.]

Physics of plasmas 10, 4378 (2003) [10.1063/1.1613963]

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Please use a persistent id in citations: http://hdl.handle.net/2128/1791 doi:10.1063/1.1613963

Abstract: Plasma-wall interaction leads to the release of impurities and neutrals of the working gas, which contribute significantly to the energy losses from the plasma edge, and therefore, crucially affects the development of thermal instabilities in fusion devices. An analytical model for impurity radiation is proposed, which takes into account the erosion mechanisms of wall material and the motion of impurity particles across magnetic surfaces. The temperature dependence of radiation losses is found to be very different from that predicted by the coronal approximation often used in considering thermal instabilities. The consequences for the development of poloidally symmetric detachment and multi-faceted asymmetric radiation from the edge (MARFE) are analyzed. It is demonstrated that the MARFE threshold principally depends on the mechanism by which working gas neutrals are released from the wall and on the neutral's properties, e.g., their ionization rate. The results of density limit experiments in Tokamak Experiment for Technology Oriented Research [Proceedings of the 16th IEEE Symposium on Fusion Engineering, 1995 (Institute for Electrical and Electronics Engineers, Piscataway, NJ, 1995), p. 470] and Joint European Torus [Rebut , Fusion Eng. Des. 22, 7 (1993)] are interpreted. (C) 2003 American Institute of Physics.

Keyword(s): J

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