Measurement and control of the fast ion redistribution on MAST

Abstract

Previous experiments on MAST and other tokamaks have indicated that the level of fast ion redistribution can exceed that expected from classical diffusion and that this level increases with beam power. In this paper we present a quantification of this effect in MAST plasmas using a recently commissioned scanning neutron camera. The observed fast ion diffusivity correlates with the amplitude of n=1 energetic particle modes, indicating that they are the probable cause of the non-classical fast ion diffusion in MAST. Finally, it will be shown that broadening the fast ion pressure profile by the application of neutral beam injection at an off-axis location can mitigate the growth of these modes and result in the classical fast ion behaviour

arXiv comment23 pages, 13 figures

Cited by in corpus (4)

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• Mitigation of MHD induced fast-ion redistribution in MAST and implications for MAST-Upgrade design
• Measurements and modelling of fast-ion redistribution due to resonant MHD instabilities in MAST
• Measurements and modelling of fast-ion redistribution due to MHD instabilities in the Mega-Amp Spherical Tokamak