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

This title appears in the Scientific Report : 2003

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

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 radiatio...

Personal Name(s):	Tokar, M. Z.
	Kelly, F. A.
Contributing Institute:	Institut für Plasmaphysik; IPP
Published in:	Physics of plasmas, 10 (2003) S. 4378
Imprint:	[S.l.] American Institute of Physics 2003
Physical Description:	4378
DOI:	10.1063/1.1613963
Document Type:	Journal Article
Research Program:	Kernfusion und Plasmaforschung
Series Title:	Physics of Plasmas 10
Subject (ZB):	J
Link:	Get full text OpenAccess
	Publikationsportal JuSER

Please use the identifier: http://hdl.handle.net/2128/1791 in citations.
Please use the identifier: http://dx.doi.org/10.1063/1.1613963 in citations.

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.